Does HM Oil Seal Head Gaskets ?

[Greg L]

Maybe a stupid question....


I have been using Pennz HM oil (5w30) on my Dodge 4.7 V-8....which a few years ago where known for antifreeze & sludge. My last OCI was actually Smittys Super S oil, and not Pennzoil.

Does any brand of High Mileage oil, with seal conditioners, actually help seal off head gaskets (as well as others) to help prevent oil contamination?


GL

 

[eljefino]

No. "Maybe" seals which go around rotating things can be helped.

Head gaskets have way too high a pressure going on in the various "holes" for this to work.

 

[440Magnum]

No. In most engines, the head gasket sees limited contact with the oil at all. In the case of a 4.7, there are pressurized galleries that pass through the head gasket to carry oil to the hydraulic lash adjusters, cam bearings, and cam lobes, but its a very small hole through a gasket material that really isn't subject to being affected by seal conditioners.

And the oil NEVER comes in contact with the areas where head gaskets are most likely to fail- the combustion chamber sealing ring and coolant passages.

I'd also add that the 4.7 sludge myth was just that- a myth. The original filler neck was a tall tube that allowed condensation to form under the oil cap. People saw that and thought "sludge!" but it was limited to just the oil cap. Later 4.7s don't even do that. The biggest problem the 4.7 had was that the first generation has a habit of spitting out cam followers (harmlessly and you can pop them right back in as many web videos show, but it shouldn't happen). People have solved that by slightly shimming the lash adjusters so that there's less clearance on cold start before the oil pressure builds. But there's a fine line and you have to know what you're doing- shim too much and a valve will fail to seat fully and then you'll get a burned valve.

 

[Greg L]

Cool. Thanks for the Mopar tip. I am fairly new to their motors.


GL

 

[datech]

I put radiator seal in a motor with a leaky head gasket. It seemed to help quite a bit. I think I used the alumaseal stuff. It would only work with a very small leak and definitely change the oil the coolant is very corrosive to engine bearings.