Originally Posted by twin turbo 281
our engines arent really designed for synthetic oils. Some people have no problems and sometimes your seals start leaking like crazy after using synthetic! mostly synthetic eats away RTV sealants. I change oil on cars everyday and I see alot of problems with oils and additives. i use regular Valvoline 5w30 and a motorcraft filter I have had no problems. Last time the motor was apart it was cleaaannn inside!! Actually suprised me of how clean it was with as many miles!
Obviously, You have no idea what you are talking about.
The ONLY thing that disolves RTVs is concentrated phosphoric acid, in a concentration that would leave the RTV the only visible thing, after it dissolved the engine block.
If your engine seals are RTV, you have more problems than oil...
The only difference in synthetic vs dino oils is the variation of the length of the hydrocarbon chains. Synthetic oil has a tighter distribution of lengths, which, in the long run, has meaning in the fact that longer chains break down easier. Paraffin is a long chain hydro.
Very short hydrocarbon chains are easier to make acidic... dino oils are random lengths, with random constituents...ethane and methane and pentane groups in the mix. Synthetic oils do not have the random BS in there; it is very regular.
Fractional Distillation (cracking) is used with dino oils to reduce the variation, but nowhere close to synthetic levels; since they are building the chains around a target value, the mix is stable.
If a synthetic 5W30 leaks, a dino 5W30 should leak. High milage oils, with seal swellers, will reduce leakage, but tend to wear seals that weren't worn before faster. And they will make no difference with ring seal, which is metal on metal.
Our engines are well known for 'poor valve seals', but at 190k miles, I really don't see much to b*tch about. My 63 tbird died at 62k miles, mostly due to quaker state oil. (paraffin) (3rd engine, about 50k each)
I use about a quart between oil changes, and Castrol Syntec synthetic gives me 3-5 mpg over Castrol GTX, depending on how I drive. I can always tell when I'm coming up on an oil change, because my mileage starts to drop...
I started using GTX about 20 years ago, because it was the only oil my bikes didn't turn into glue...
You can treat your engine however you want. Mine will still be running at over 300k, if past history is any indicator. Yours is not as likely to be running next year.