Can You Use Synthetic Oil In A Flathead V8 Engine?

Not going to rebuild yet, and have some soking issue due to rings. Can I run synthetic oil and will that help with the smoke?

 

I think synthetic oil in any flathead (even a fresh rebuild) is a bad idea. Flatheads leak even with regular oils. The technology just isn't there to use synthetic. I can't answer your question about the smoke.

 

Thanks

 

Why is synthetic more prone to leaks than regular oil, even if they are the same weight?

 

They say if a flathead has NOT been apart to run non-detergent oil,probably 30w, so as not to disturb all the crud in the motor...If you use detergent it will dislodge a whole lot of stuff.......

 

Search me. All I know is that I made the mistake of listening to oil gurus and put Mobil 1 in my 351w (yes I know it's not a flathead) and it pissed everywhere. Went back to 20/50 mineral, no more leaks. Go figure.
Paul.

 

This 276 flathead built by Motor City Flathead years ago has always and only used synthetic oil with no leaks.

 

Will it help with the smoking? Talking about an old worn out motor like yours. It might, because it won't oxydize as easily but that means if it ain't burnt, more oil (instead of smoke) will be coming out into the exhaust and breather system. That means more mess, dripping on the driveway. So, is that what you want, to trade smoke for dripping oil?

As far as a freshly built motor that don't smoke or burn oil, that's a different matter. I cant see any advantage to going to synthetic. The primary advantage of synthetic is it's potential to operate at higher temperatures; temperatures that the oil will never attain in an older design, or any motor designed in the 1930/40s. Whether it will work or not, I'll never know because I would never pay the higher price just to find out since my old motors work just fine on regular oil.

 

If the engine is rebuid and totaly clean inside should it not be a problem to use
I have used synteic oil in a 455 olds that never have been restored but the pan was cleand out and it don't leaks.
I have used it in restored old eniges to and it works fine and don't leak more than other old engines

 

I've never used synthetic oil in a auto engine and probably won't due to the higher price. I have had over 30 years of experience with synthetics in turbine engines. Since reciprocating and turbine engines are fundamantally different, I only address the part about leaks. Ester based oil in one of the thinnest oils in existence. If the seals aren't up to par, it will leak out. Turbine engine oil is only sold in cans since it will find a way out of any other type of container. Automotive synthetics are blended different that turbine engine type oils so there is no comparison between them as far as lublicating qualities but they both like to find there way out of a seal.

In the old days we would put a can of STP additive in with some straight grade oil to get it to slow the oil passing the worn out rings and intake valve guides. This was only a temporory fix. Most people would do this before they took it in to the dealer to trade for a new car.

If you have one or more broken rings in that motor, it will score the cylinder walls or you might burn a piston or a cylinder wall where the gas it passing through. I wouldn't recommend running it too long that way.

 

put some Lucas in there...similar to stp

 

^^^^^ Lucas is good stuff. I run it in several older wore out tractor engines and it cuts oil use by a lot