[RMJacobs]

I got this info from a page i was reading about car maintenance. I had never heard this before. Do any of you know if this is true? I normally change oil about every 4,000 miles.

That oil change? Turns out every 5,000 miles is often enough. New oil has chemicals that eat away the catalytic converter, says Donny Seyfer, a Colorado-based certified master technician, and changing oil too often can damage that pricey part.

 

[wskaiser]

I have not heard that, it may or may not be true. Just because he is a certified master technician does not automatically make his opinion any more correct than anyone elses and in this case it is probably just an opinion.

 

[6NOVA4]

I can see the oil damaging a cat if it being pushed thru the engine, being partially burned up in the combustion chamber and some being burned up in the cat. My guess would be it aids in the deterioration and causes the catalyst material to break up in chunks. Contaminates it like coolant or excess fuel or lead substitues and renders them inefficient. And that's my opinion cuz Im a ASE certified Master Technician too....

 

[RMJacobs]

I can see the oil damaging a cat if it being pushed thru the engine, being partially burned up in the combustion chamber and some being burned up in the cat. My guess would be it aids in the deterioration and causes the catalyst material to break up in chunks. Contaminates it like coolant or excess fuel or lead substitues and renders them inefficient. And that's my opinion cuz Im a ASE certified Master Technician too....

I like your answer.. thanks.

 

[Racinfan83]

I use Mobil 1 synthetic in my truck, change it religiously every 3000 miles, and the truck has 120k on it. Dodge trucks are kinda notorious for having "cat failures" - but mine is still going strong. Guess the guys opinion doesn't hold too much water with me...:no::no::no:

 

[big dog ss]

i change my oil- filter every 2500-3000 miles in my daily drivers. my wife's 96 pontiac has 220.000 and my 98 jimmy has 188,000 miles.. never had a problem with either cat.. and either one burns any oil between changes... and this comes from a guy that has a degree from the school of hard knocks!!:yes:

 

[supernovanator]

When it comes to oil miles don't really matter as much as everything else. You can probably go 5000 miles on oil if you drive highway miles only, where the engine is at a constant low rpm. In city and hard driving you need to change the oil sooner because it takes more revolutions of the motor to go the same distance. Oil life meters in new cars calculate oil life by the revolutions of the motor, speed/time, etc... NOT by miles.

As for the oil having chemicals that eat the cat up... At what point is the oil NOT the same oil you put in the car? Unless these magic chemicals evaporate they will still be in the oil when you drain it out of the car, so that argument really doesn't make sense. Not accusing anyone of anything, but waiting too long to change your oil can have some bad effects on your motor. And what happens when the majority of people have car problems? Yeah... they take it to a mechanic! Sometimes even a master certified one

 

[67SHOEBOX]

I use Mobil 1 synthetic in my truck, change it religiously every 3000 miles, and the truck has 120k on it. Dodge trucks are kinda notorious for having "cat failures" - but mine is still going strong. Guess the guys opinion doesn't hold too much water with me...:no::no::no:

I have a Dodge truck also and use synthetic oil and my truck runs like the day I baught it:yes:

 

[veno]

I think he was referring to Zddp.. every combustion cycle burns off the oil left on the cylinder walls.. the left in place ZDDP protects the walls from the rings on the way back up... the flushed exhaust disposes of the burnt used ZDDP straight to the CAT... the high concentrations of ZDDP destroy cats..... thats why modern oil has less then 800ppm of ZDDP.. prior to the gl4 rating the gl3 rating oils had less then 1000ppm of ZDDP...

 

[6NOVA4]

As for the oil having chemicals that eat the cat up... At what point is the oil NOT the same oil you put in the car? Unless these magic chemicals evaporate they will still be in the oil when you drain it out of the car, so that argument really doesn't make sense. Not accusing anyone of anything, but waiting too long to change your oil can have some bad effects on your motor. And what happens when the majority of people have car problems? Yeah... they take it to a mechanic! Sometimes even a master certified one

Hmm I don't know I guess when the chemical composition has been changed due to the heat cycles of the engine???? over time the oll degrades and breaks down? I never took chemistry.

 

[6NOVA4]

I think he was referring to Zddp.. every combustion cycle burns off the oil left on the cylinder walls.. the left in place ZDDP protects the walls from the rings on the way back up... the flushed exhaust disposes of the burnt used ZDDP straight to the CAT... the high concentrations of ZDDP destroy cats..... thats why modern oil has less then 800ppm of ZDDP.. prior to the gl4 rating the gl3 rating oils had less then 1000ppm of ZDDP...

^^^^

yea that. He puts it more eloquently.