Sometimes it's needed, but not always. If you find it's needed. go to your local drug store and ask them to get you some sodium silicate. It comes in a mayo type jar, is the same stuff as Moroso's and costs a lot less. An old mechanic turned me on to the stuff in the 70's when I cracked the head on an old Rambler--sealed it right up! It stays in liquid form until exposed to the atmosphere, then it turns like glass-hence it's common name "Water Glass".
Farmers used it to coat eggs that have thin shells to prevent breakage on the way to market.
When I finally pulled the Rambler apart, I found cracks 1/16-1/8" wide thru all the exhaust seats that were sealed by this stuff. You should never drive thru the Nevada desert at 80+ with no water in your car!!! Especially in a 60 Rambler.