Oil filter by pass thoughts

[Real McCoy]

I am wondering who runs their wet sump motor with a oil filter by pass working and who runs with it blocked and why do you do what you do? Next is if you run the by pass blocked what make filter do you run and why that make if you have a reason? There is no right answer in my mind but I am curious as to what others are doing. I have run the BB motors in my big tire car both ways but right now I am running it with the by pass working. Just curious what other people who drag race are doing right now. Thanks, RM

[Pick]

I've always been leary of trying it, but PW and others have about convinced me to give it a whirl. In fact, I'm going to go ahead and do it next time I change the oil - unless I waffle again between now and then...:rolleyes:

[T. Jerman]

The positive thing about is that 100% of the oil will go through the filter. The negative is that if you have to much oil pressure on a cold eng. you can blow the filter off. That is what my eng. builder told me.
I have run my engine with the by-pass plugged for 3 yrs. and have had no problem. My engine has alot of oil pressure cold so I just let let the engine warm up before I really hammer it.:D
Thats all I know about it and I'm sure there is other reason's of good and bad.

[Scruffy]

I tried running no bypass on my dragster for a couple of weekends back when I was bracket racing.I used a regular Fram orange filter and the filter media collapsed from the exessive pressure,I assume.When I took the filter off it felt like there was a tennis ball shaking around in the can.The Fram HP or the Moroso filters may work better for the higher pressures.All I can say to anyone who does it is use a good filter.Something that is intended for the higher pressures.Good Luck

[Tom Griffin]

I run with the bypass valve. I also use WIX oil filters. I talked with my engine builder about this topic when my short block was being built, he told me not to plug the bypass valve. I also called Milodon to ask them since I was using their pump and pan at the time... they told me they recommend not plugging the bypass.
I had a chance to visit the engine building room at Hendrick Motorsports so I asked one of the guys assembling the engines and he said don't plug the bypass valve.
The bottom line is I now have three years on my engine, it's not babied and driven tons of miles each year, I pull the pan every winter to check on things and everything still looks excellent.
I really think if you are the type of person who changes their oil and filter on a regular basis it does not make any difference either way. Everyone will have a different opinion on this topic I am sure:D

Tg

[Paul Wright]

This is a myth.
There's no danger of oil filter blow off because the pressure relief valve controls the system pressure, not the bypass. Oil filter blow offs happen when the pressure spring in the pump is shimmed. I've seen this happen on a Corvette. Guy thought too much was just right.

Really high cold pressure is the result of thick oil and or too high a pressure relief spring.
The ONLY problem is if you don't change your oil filter or it gets plugged.
When it gets restricted you will see a drop in oil pressure. If you change your filter when you are supposed to you won't have any problems.
The benefit is 100% of the oil going through the filter.
Lingenfelter recommends this mod (it's in his book). I do too.
I laso recommend cutting your filter open when you change it and inspect the pleats. You want to look for early warning signs of impending doom. Changing a failing rod bearing is preferable to a hole in the block.

[Real McCoy]

I used a blocked by pass some years ago. I also used a PH30 Fram filter due to header clearances and no room for a long filter. I started having issues with oil pressure after two races. It acted like the pick up tube was broken so I pulled the motor and it was in fact cracked. Fixed that and again after a couple races oil pressure got goofy just like before so I pulled the motor again but this time found nothing wrong. I replaced the pump and the pick up even though I found nothing wrong cause pulling the motor with the 2 1/4 headers was brutal. The problem continued, after a couple races the oil pressure got goofy like the pump or pick up was bad. A buddy told me to get that short bodied Fram filter off the car and use another brand so I did and that resolved the issue. The Fram filter has apparently got a finer filtering media and it was stopping up or something. Running a Purolator, Wix, or an NAPA gold filter and it was fine. Ran the motor for 2 yrs and over 300 passes before I freshened it up and it looked like new inside when I pulled it apart but I have never seen a problem with scuffed bearings even running the by pass like i am now. I put the by pass back in and have used it ever since but now I'm thinking I want to go back to a blocked off by pass. The headers I have on this chassis will allow me to run the long body filter which I like. We always run blocked by passes on all the dirt track motors built at the engine shop. Thanks for the thoughts. RM

[Paul Wright]

This should maybe be in Best of Tech because it's a FAQ.

[stock z/28]

Hi.

I have used them both ways and I don't see a big difference.

There is another thread here somewhere about this. My impression is that just about all common filters have an internal bypass anyway, so if the filter does become a restriction it will bypass internally. I think there is a couple of filters that don't have the internal bypass, but i'm not sure which ones they are. Possibly the tall 60 series style truck (commonly referred as 2 quart) doesnt have the internal bypass.

My concern on filters is that they don't have an anti-drain back valve.



Jeff

[65 Post]

In my race engines I use a billet oil filter mount from Jegs without the bypass. I just like the oil going through the filter. I always used an AC Delco PF35. Now they're discontinued so I use a 1218. I tried a Fram on advice from a friend. My oil pressure went crazy. Up, down, I got frustrated with it and went to put the AC back on. When I unscrewed it a funny thing happened. NO oil came running down my hand. After I had it off, I looked inside and it was only half full of oil. Or half empty. All depends how you look at it. That was my last deal with a Fram. It's Delco, Wix or Systems 1 for me. I also read on another site that Wix makes NAPA filters. They even have the same numbers on them. My opinion. Dave

[DriveWFO]

What is a good alternate for the PH30 filter?

[L78steve]

I always use the Fram racing filter,It has the heaver shell to protect from blowout.And I always prefill the filter before installation.Whether you plug the bypass or not it won't make any difference if you use a filter with a large enough capacity and you warm the engine before revving.So why plug it at all?

[Jake]

I've always plugged the bypass in my engines. I have always ran AC Delco PF1218 filters also since a WIX I tried failed internally and I lost alot of press. I always stayed ahead by changing and inspecting the filters often. I may try a Car Quest brand filter on my next engine after seeing a cutaway of a few popular brands.

[L78steve]

As far as the drain back valve concern,you would only need them if the filter is tipped up to allow draining.My chevy pick-up has this almost upside down filter so it uses a PF52 that has a check valve.

[Jake]

As far as the drain back valve concern,you would only need them if the filter is tipped up to allow draining.My chevy pick-up has this almost upside down filter so it uses a PF52 that has a check valve.

Really,so thats what its for. I always thought it was so the oil would stay "primed" in the pasage to the pump instead of draining back into the filter. Kinda makes more sence I guess. Now I feel stupider.:D

[stock z/28]

Hi,

When I found out the PF35 were going to be discontinued in bought all could find.

My understanding on 1218 was that it was to prevent drain back on the oil coolers on chev trucks.

A few years ago I talked with AC and Fram about the addition of the check valve in a filter used in a race application, and neither would recommend its use. It would seem to be a restriction in oil flow.

[Pick]

I haven't studied oil filters all that much, but usually use the Purolater Pure One filter. Anyone seen a study or have experience, good or bad, with this filter?

[David_D.]

I run the NAPA Gold 1061R race filter. Never had a problem with NAPA filters.

[Paul Wright]

I think the main reason changing the part number was the problem of counterfeit oil filters. AC-Delco has a serious problem (http://www.acdelco.com/parts/counterfeit/index.htm) with that.

[Real McCoy]

As I said earlier with the by pass blocked the only filter I had any trouble with was a Fram PH-30 and it seemed to clog up. I felt it had a finer filtering media than all the other filters I used. I changed the oil today and just left everything the same as it's been since spring of 2005 when I freshened it last. Oil filter by pass working, 20X50 oil and a PH-30 filter. I took the, If it isn't broke don't fix it, route. Thanks again for all the thoughts on this. RM

[bowtie0069]

I stopped using the Fram stuff after reading about some pressure loss when using them--I switched to K&N and it did increase the oil pressure. On the junk 350 I'm running right now I used a Fram and it seems to have great oil pressure, but when I put the good one back together, I'll switch back over.

[stock z/28]

Hi,

I think the Ac number change was more than a counterfeit issue.

The 35 has no drain back valve. The 1218 does.

Both have an internal bypass, which in my opinion practically makes blocking the valve in the aluminum filter adapter a moot point. The only issue is what differential pressure is required to activate the bypass. But the assumption that blocking the adapter bypass creates a situation that all oil is filtered is wrong (in my opinion) Like I have stated earlier there is a few filters that do not have an internal bypass, so that in my opinion if you use on of these filters with a blocked adapter you would get a situation that would allow a 100 percent filtration of oil flow (as long as the differential passage under the main cap (usually a small cup plug or ball brg) is replaced after cleaning). This would be very good on a fresh engine to remove break in material as well other debris.

Jeff

[Real McCoy]

Well I cut open several of the PH-30 Fram filters and there is no by pass in them unless the metal dished plate at the bottom which pushes the media against the top plate would be considered a by pass system but it's not a spring steel. I also know if it was intended as a by pass it failed when I had my past issues using them because when the media blocked up I lost pressure until the oil got hot and thinned out, then it acted OK. I couldn't live with that goofy stuff and reinstalled the by pass. I personally think if you use a blocked by pass you need to use a non Fram filter and you should use a long filter so you have more media area. JMO. RM

[Tom Griffin]

Just incase it has not been shared before here is a like to a older oil filter study. It has some pretty interesting info in it. I am not sure but this might have been partially supported my Milwaukee School of Engineering... my old school:D

http://people.msoe.edu/~yoderw/oilfilterstudy/oilfilterstudy.html

Tg

[Real McCoy]

Darn Tom that study sure made me feel dumb.......LOL. The engine shop I hang out at has always used purolator filters. Guess I should have as well.......LOL. I have never had any problems with the Fram filters but I also change oil more than anyone I know so that may be why. I think the reason the Fram seem to clog up is because they have no surface area compared to the others. I see Wix filters in my future. Thanks for the study. RM

[DriveWFO]

So what cross-references with a PH30 filter :confused:

[Real McCoy]

I'm going to my local parts store in the morning and hope to find out what Wix will work. My buddy claims he can call the Wix engineers so hope to learn more. I'll post if I find out. RM

[Paul Wright]

I also found the same study oil filter comparison (http://minimopar.knizefamily.net/oilfilterstudy.html) but at a different URL.

I still think plugging the bypass makes more sense rather than having TWO bypass routes.

I've done some more checking and you can buy oil filters without a bypass, but they all are expensive. Jomar, Moroso, Wix racing and others for example.
Some racing filters are higher flow but apparently have less filtration (micron size) to prevent early plugging. The assumption is the engines are assembled in a clean environment and they don't run for a long time. 500 mile oil changes (and rebuild)!

There is also the 'Bypass filter" systems which route some oil though a tighter filter element an run the rest through a "looser" but full flow filter element. These systems are expensive but appear to help extend life on very high mileage engines and therefore presumably pay back the investment.

I seem to recall looking in the filter paper catalogs at the parts store and they list "drain back" and "no drain back" filter part numbers.
There is anecdotal evidence of certain filters causing lifter noise in some situations, presumably due to low oil pressure when the oil is bypassed back into the pan.

Back to the original question of plugging the bypass, IMO, there is no drawback as long as the filter is changed regularly. As long as the filter is clean, all the oil should flow through the media.

If it does become restricted and it's internal bypass opens, this should show a drop in oil pressure on the gauge. Changing the filter should restore the pressure.

[Pick]

This is exactly why I have never been able to make up my mind on this subject. There is no consensus whatsoever on whether running a bypass or plugging it is the best route to go. By default I've stuck with the stock design and left the bypass open. I think I'll leave well enough alone.

[DriveWFO]

This is exactly why I have never been able to make up my mind on this subject. There is no consensus whatsoever on whether running a bypass or plugging it is the best route to go. By default I've stuck with the stock design and left the bypass open. I think I'll leave well enough alone.

FWIW, I running an oil filter adapter prepped & plugged by Paul and haven't noticed anything different as far as the oil pressure is concerned.

[NovatoriusRex]

FWIW, I running an oil filter adapter prepped & plugged by Paul and haven't noticed anything different as far as the oil pressure is concerned.

I'm running a Moroso remote filter adapter, also without a bypass, with an AC PF35L filter, and haven't noticed any issues either.

[Real McCoy]

Well my friend at the motor shop does this for a living and he and his Dad before he died have investigated all this stuff already. His Dad was one of my best friends and he gets credit for the little I do know.......LOL. Now I do a little work up there but it's done their way and I do all my personal motors there but when I do my stuff I do it my way....LOL. Now I get a little hard headed about stuff sometimes and even though they are smarter than me I don't always do what they suggest. They do motors that are abused by round trackers and require different things than a Drag motor so I don't always follow their rules and I usually have no issues doing it. That's how we get to these discussions. Even a blind dog can find a bone sometimes, looks like I just did. Thanks, RM

[stock z/28]

Hi,

I didn't get a chance to review the complete filter article Tom linked, but I take it that the Wix was a good choice?


Like I stated earlier I am real concerned with using a filter with the drain back valve in a high perf application. I generally use a NAPA filter that does not have this valve. I can get the number of the filter if any one wants it. I think WIX may make these filters, but I'm not sure.

I have never spent the money on a non bypass filter for my own use. I have used them on remote systems that were used on endurance engines. My only real reason for wanting a blocked bypass system was to guarantee filtration on a new motor. I guess a review of differential pressures on the various bypass systems would help, but that sounds too complicated for me to mess with (I am pretty lazy).

Like I said I have used the adapter both ways.

Jeff

[Real McCoy]

In this study Purolator and Wix rated high. Fast read is hit the Whats recommended and Not recommended filters. Couple of paragraphs boil it down pretty well.......LOL. RM

[John65ss]

The 35 has no drain back valve. The 1218 does.

Both have an internal bypass, which in my opinion practically makes blocking the valve in the aluminum filter adapter a moot point. The only issue is what differential pressure is required to activate the bypass.

Neither the PF1218 or the PF35 has an internal bypass. Tear one apart and you will see that there is no bypass built into the filter. The Motorcraft FL1-A is a good example of a filter with a bypass.

I still cannot figure out why people insist on messing with a perfectly adequate small block chevy oiling system. I cannot think of ANY street driven application were you need to worry about making modifications to a system that the engineers got right in the first place.

IMO, if you want to run 3000 worry-free miles without an oil change, leave the bypass functional! Leave the blocked bypass for the race crowd. I have never heard of one instance where catastrophic failure was caused by leaving a filter bypass operational. If the bypass served no function, it would not be a part of ALL production engines.

Just my opinion... I am by no means a professional, but for a street/strip car, I just don't see the need to disable the bypass.

[Pick]

John has raised an interesting question in my mind. The guy in the filter article was comparing filters for a Ford 302. The AC filter he cut open clearly had a bypass valve.

If in fact the AC 35 and 1218 do not have internal bypass valves, could it be the Ford uses only a filter bypass whereas Chevy uses the adapter bypass? If this is so, then maybe none of the filters for a Chevy have bypasses in them.

Any one know for sure?

[Real McCoy]

Just curious what other people who drag race are doing right now. Thanks, RM

By pass is fine for a daily driver but when someone modifies a motor the things the GM engineers designed are not always good enough. Then the filter study suggests all filters are not created equal. RM

[John65ss]

If in fact the AC 35 and 1218 do not have internal bypass valves, could it be the Ford uses only a filter bypass whereas Chevy uses the adapter bypass? If this is so, then maybe none of the filters for a Chevy have bypasses in them.

You are correct sir. Ford 302 had no block-mounted bypass. It is in the filter. Chevy used a block-mounted bypass, so the filter is constructed with no bypass. :)

I'd like to see some examples of a filter bypass causing catastrophic failure. In my mind, dirty oil is better than no oil.

If something goes wrong and the filter gets plugged with debris, you'll have a huge pressure drop and flow restriction through the filter, which means the bearings and other parts are getting oil at greatly reduced pressure / flowrate. Bypass just makes sense to me - when the pressure drop through the filter becomes too great, at least you are sure to have SOME lubrication getting to the engine, and not just a trickle through a plugged filter.

As I said... I'd rather have dirty oil than NO oil. :)

[Paul Wright]

I am a big proponent on the stock Chevy oiling system. GM engineered a system that takes into account people that don't change their oil.
The bypass is indeed a failsafe in case someone doesn't change their oil filter.
Dirty oil is better than no oil, however as Lingenfelter says, any true hotrodder would never let their oil get that dirty.

The reason for plugging the bypass is to be sure no oil get's bypassed ever....even during cold start. Race cars aren't driven in the winter so they don't need to bypass until the oil thins. I don't recommend using thick oils if the bypass is plugged.

Racers also have oil pressure gauges which give an indication of pressure drop. A true hotrodder monitors his oil pressure.
You have a major engine problem if a filter plugs instantly from that much debris.

I think the observation about the location of the bypass for Ford and GM systems may have been correct at one time but the ACDelco oil filter page refers to filter bypass. They make filters for other brands so I don't know if this applies to old GM V-8's. I think having two bypass vlaves would be counterproductive.

I'm sure the debate will continue. I've been testing it on my tow wagon for the last 2 years (about 20,000 miles).
The engine is coming out to replace an apparent broken ring. I'll inspect the bearings and post pictures.

[novaboy009]

Paul, would you like a set of total seal rings for that tow wagon?

Kev (might just have a set sitting around ;) )

[Paul Wright]

FWIW, I running an oil filter adapter prepped & plugged by Paul and haven't noticed anything different as far as the oil pressure is concerned.

Yes, but your transmission did break. Coincidence? I dunno.... :rolleyes:

[DriveWFO]

Maybe I missed it somewhere, but has anyone posted an alternative to the PH30 filter?

[stock z/28]

Hi,

Well it gets complicated I guess.

First let me say that I never use the 1218 in a race application so I have never dissected one, but my tech guy at Delco told me when they first came out the did have a bypass system as well as a provision for drain back control. He stated that they did not recommend (I have talked with other filter manufactures as well, and everyone has recommended they not be used in high perf application) for racing.

Second, Every 35 I have cut apart has a bypass system. This is they way it was explained to me in the 70s by AC (it wasn't Delco then) there is spring plate in the bottom on the can that applies pressure to the filter element sealing it against the mounting base. If the filter becomes cloged the oil pressure will depress the spring a small amount and permit oil flow, effectively bypassing the filter media. This also applies to very high viscosity oils especially in cold weather (the basic design oil pump pick up screen (pre-3/4) had a bypass as well). As I stated earlier I have no Idea what the differential pressure would be that would operate either system (filter or adapter). I wasn't aware of the filter bypass system until about 1975 when I was involved with some factory backed Corvette road racing guys. A Gm engineer pointed it out to me, and gave me a recommendation on a filtering system to use that would not bypass.

Third, I totally agree that a small block chevy has a great oiling system as is. My only interest in blocking the bypass is to force as close to 100 percent filtration on a new motor. In my opinion no mater how well you clean components during assembly you will still generate (or a chance of it) some degree of debris. I generally use a 20 w oil- a blocked adapter- and a specific filter for this brake in. Then I change the filter (and maybe adapter) and oil. Its hard to find a filter that doesnt have some type of internal bypass that still uses small filtering media, but a couple do exist.


Im certainly not an oil filter expert and I really dont care what someone does with their adapter. Im just giving my view on what I have been told, and learned over the years. As far as the ford not having a bypass in the block I agree and a filter for that application may have to have a much different type of valve design. I have no Idea.

Was it Einstein that said its all differential pressure?

[John65ss]

I am a big proponent on the stock Chevy oiling system. GM engineered a system that takes into account people that don't change their oil.
The bypass is indeed a failsafe in case someone doesn't change their oil filter.
Dirty oil is better than no oil, however as Lingenfelter says, any true hotrodder would never let their oil get that dirty.

If your oil is not that dirty, than it is no big deal if it bypasses, right? ;)

This debate has gone on for years, but I will continue to run a bypass. I like the "belt and suspenders" the bypass provides, and no one will ever convince me that any harm has come from running a bypass. There are a lot of 200k mile small blocks that are running just fine with fully functional bypass valves. When you consider that most of these 200k mile engines did not see 1000 mile oil changes, that tells me that the minor amount of dirt that bypasses does not hurt a darn thing over the long haul. :)

[DriveWFO]

Yes, but your transmission did break. Coincidence? I dunno.... :rolleyes:

The classified work done to the adapter was good for another 25hp, just enough to push the tranny over the edge :D

[stock z/28]

One last thing John. If you have some tech info on the AC filter change I would be interested if you could post a link. I called Delco this morning and he said (sadly) that the 35 is still discontinuied and that the 1218 does have an internal bypass (still).

Jeff

[DriveWFO]

The AC Delco website says their PF454 filter cross-references to the Fram PH30.

I just found the WIX compatible filter (non-bypass):

Part Number: 51069
UPC Number: 765809510692
Principal Application: GM Family of Cars/Trucks (64-97)
All Applications
Style: Spin-On Lube Filter
Service: Lube
Type: Full Flow
Media: Paper
Height: 4.338
Outer Diameter Top: 3.660
Outer Diameter Bottom: Closed
Thread Size: 13/16-16
By-Pass Valve Setting-PSI: None
Beta Ratio: 2/20=2/26
Burst Pressure-PSI: 225
Max Flow Rate: 9-11 GPM
Nominal Micro Rating: 19

Gasket Diameters
Number O.D. I.D. Thk.
Attached 1 3.444 3.100 0.260
http://www.wixconnect.com/images/filters/5673_1.gif

[Paul Wright]

I noticed the WIX has No bypass pressure. That looks like the one to use. Compettion black and everything.
I may go pick up a case of those from Napa.

Kev, I'd love to have those rings. You in a early christmas mood or what?

[DriveWFO]

I noticed the WIX has No bypass pressure. That looks like the one to use. Compettion black and everything.
I may go pick up a case of those from Napa.

Kev, I'd love to have those rings. You in a early christmas mood or what?

I found a local supplier and the filters are around $5/ea. I also presume that no bypass pressure meant it didn't have the bypass in it.

[Real McCoy]

I found the same info as WFO did. Going to the parts store in a short and get one to try it. RM

Part Number: 51069
UPC Number: 765809510692
Principal Application: GM Family of Cars/Trucks (64-97)
All Applications
Style: Spin-On Lube Filter
Service: Lube
Type: Full Flow
Media: Paper
Height: 4.338
Outer Diameter Top: 3.660
Outer Diameter Bottom: Closed
Thread Size: 13/16-16
By-Pass Valve Setting-PSI: None
Beta Ratio: 2/20=2/26
Burst Pressure-PSI: 225
Max Flow Rate: 9-11 GPM
Nominal Micro Rating: 19

Gasket Diameters
Number O.D. I.D. Thk.
Attached 1 3.444 3.100 0.260

[DriveWFO]

NAPA shows the same part# for their Gold brand of filters (#FIL1069).

http://partimages.genpt.com/partimages/505665.jpg

[stock z/28]

Hi,

I think that is the same filter that I get from napa. They will usually make you a good deal on a quanity. If you want to check it out the napa no. is 21069.
These are about the only filter I have used since Delco droped the 35-25. I have had excellent luck.
Jeff

[DriveWFO]

Hi,

I think that is the same filter that I get from napa. They will usually make you a good deal on a quanity. If you want to check it out the napa no. is 21069.

Jeff

Yes, that's the same as the NAPA filter I just posted above.

[John65ss]

One last thing John. If you have some tech info on the AC filter change I would be interested if you could post a link. I called Delco this morning and he said (sadly) that the 35 is still discontinuied and that the 1218 does have an internal bypass (still).

As I understand it, the spring that keeps the filter element seated against the back plate is NOT a "bypass". It is merely there to keep the filter media sealed and ensure that nothing leaks past the media. Dissect a Wix (as shown above), and you will see the same spring (Wix uses a coil spring instead of a "leaf"). I cannot see how pressure could act against this spring.

Open up a FL1-A to see a true bypass valve.

Also note that AC Delco has multiple filter suppliers, and not all PF1218 filters are created equal. I have seen these made by Delphi, Champion Labs, and a third Mexican supplier. None were counterfeit (I checked with AC Delco reps and even sent them a filter to inspect - the Mexican one).

I maintain that the PF1218 DOES NOT have an internal bypass, and the tech you spoke with is misinformed. That is my opinion, and I am sticking to it! ;)

[stock z/28]

The pressure is generated by surface area of the filter as the element becomes a significant restriction. No restriction = little pressure.

As I said I have never had a 1218 open. I dont know whats inside it, or who makes it.

I dont want to change your opinion, just explain mine.

Jeff

[John65ss]

The pressure is generated by surface area of the filter as the element becomes a significant restriction. No restriction = little pressure.

Think about where that spring is located, and how pressure acts on the spring. There is NO WAY that pressure can act to deflect that spring and bypass the filter. Pressure on the "bottom" of the filter (spring side), equals pressure on the "top" of the filter (backplate side), so it just won't happen.

EDIT: Both Ends of the filter element are exposed to the same "dirty side" pressure. Since pressure is equalized on both sides, there is no differential to act against the spring.

:)

[stock z/28]

Hi,

I agree with you John. Like I said Im certainly no oil filter expert, and really dont know the specifics of the differential, I brought the same point to the ac engineer years ago and it seemed be a point of clearance between the housing and the element. But like I said I agree that it would like it would be equal. Im not sure what the actual surface area (where the oil enters is).

I have to run, be back Later

Jeff

[Real McCoy]

Just got home and I bought a Wix 51069 and it's going on the race car. Darn thing wasn't even expensive really $6.00. I change oil and filter every 25 passes so if I avoid losing first round for awhile I'll cut it up and see how it does. RM

[David_D.]

This link shows the PF1218 as having a bypass.

http://www.midwayautosupply.com/detailedproductdescription.asp?9163

AC-Delco PF1218 Oil Filter

An engine run with dirty oil won't last. Keep it clean with ACDelco Oil Filters that offer high-flow efficiency, the latest filtration technology and durability.

ACDelco Oil Filters filters are engineered with the best filtering element and technology to trap particles as small as one-third the width of a human hair. An ACDelco Oil Filter helps protect your engine in many ways:

• Excellent filter capacity, enhanced efficiency, consistent flow management and high durability make these oil filters among the best you'll find
• Tight seals prevent unfiltered oil from entering your engine
• Consistent, dependable oil filtration throughout the filter
• Antidrain back valves retain oil in the filter for quicker engine lubrication during start-up
• By-pass valves help keep the engine from becoming oil-starved during cold weather starts or if total filter blockage exists

[stock z/28]

Sorry I had to run earlier.

John I really do agree with you on the basics, and I wish I could be more informative, I just dont know much about it.

Maybe if you contact AC they can give you an explanation. All I can say is what they have informed me about. As I said I have never had a 1218 apart, but I know its different than a 35, and I wont use one in a HP application. That's when I switched to the NAPA.

To add to the mystery, I have never seen an element collapsed inward in an AC filter, and I have in other brands used with high viscosity oils.

I was pretty die hard AC until the drainback deal.



Good luck

Jeff

[Pick]

This has been a very helpful and informative thread and has answered a number of questions I've had for a long time.

Thanks to WFO and the others for finding those WIX and NAPA numbers. I will be switching to them next oil change.

[stock z/28]

Hi,

Well I cut a "new'" 35 apart today to look at it and I agree that it would appear that as John said "dirty" oil would equalize pressure, so I really cant say how a bypass works on this.

I called AC (again) and they say that even the later manufactured 35s had an internal bypass and the 1218 does as well. I asked him to fax me a copy of the tech info and he said it was basically double secret type internal only type stuff and wouldn't fax my anything. So I must say Im more confused now than earlier in the day (thanks John).

In all seriousness I would always want to be accurate in what I say, and I feel real shaky on this. Even though Delco still say it does. Im not sure.

I have tried to think of a practical way test a filter to see if it has the "bypass" capability but I cant think of an easy way to do it.

So I am still confused, as always just more so I guess.

On a side note I use Chev oil filters on all of my honing equipment and parts washers. I take the oil filter adapter and cut the threaded hub out and weld it into a drilled piece of steel. Drill one more hole in the plate and braze or weld a fitting in the top of threaded hub and its basically done. I weld a small angle to it to mount it. It makes for a real cheap filter system.

Jeff

[Tom Griffin]

That's the wix filter that I use... the black beauty as I call it. From time to time I take a brand new one and cut it apart just to see if they have changed anything. I always cut my old filter apart just to see what I can find. Nothing but love for the black beauty:D
Tg

[DriveWFO]

That's the wix filter that I use... the black beauty as I call it. From time to time I take a brand new one and cut it apart just to see if they have changed anything. I always cut my old filter apart just to see what I can find. Nothing but love for the black beauty:D
Tg

That's good to know!

[Paul Wright]

This has been a very helpful and informative thread and has answered a number of questions I've had for a long time.

Thanks to WFO and the others for finding those WIX and NAPA numbers. I will be switching to them next oil change.

I agree. This should go in "Best of Tech" when everybody is done commenting.

[John65ss]

So I must say Im more confused now than earlier in the day (thanks John).


Glad I could help! :D

In all seriousness, I really can't see HOW it can bypass. I wonder if the tech is confusing the anti-drainback with a bypass. I HAVE seen PF35s (late ones) with anti-drainback valves. All PF1218s have 'em. If I had to guess, I bet this is what the tech is mistakenly calling a "bypass".