MikeM

It's a moot point because the OP said he wasn't overfull and couldn't smell it but now, I'm curious how much is too much?

We all know that carburtor cars with chokes would put gasoline past the rings and into the crankcase in cold weather. Could do it in hot weather too.

AZDoug

The PCV systems scavenge vapors from the crank case, gas evaporates off when the car is at temperature*. Oil dilution was serious problem with the road draft tube system, the PCV eliminated most of the concerns. Having a gallon of gas mixed with your 5 qts of oil is not a good idea, but anything above 1/2 qt of gas should show up on the dipstick with an abnormally high reading.

FWIW, the owners manual for my '33 Chevy says in winter time to add a quart of kerosene to 10 wt oil to thin it when operating below -15F.
Doug

*look up thin film evaporators, the continuously changing film of oil on the crank case walls, lifter valley walls and cylinder walls, rods, etc will flash light hydrocarbons like gas off rapidly at operating temp.

Frankie the Fink

Draw your own conclusions:

https://www.lubricants.total.com/fue...es-and-effects

dplotkin

Here's mine, yours is the second corporate link posted here, both are interesting and are probably close to right on the conclusions they draw yet both sell oil. Hardly independent and disinterested, they like most of us have an axe to grind or a dog in the fight or whatever.

We all know the answer here, if you grossly contaminate oil with fuel and drive around for long its going to cause damage. If an engine is cranked from -15 and immediately matted its going to cause damage. But far more likely and far more often the cause of premature bearing failure is contamination of the bearing surface from dirty oil and/or a lack of lubrication caused by sludge. I agree fuel contamination can cause damage, but I'm not persuaded that this is a common cause. How much gas in the oil is too much? What ever amount it is that prevents a film. Probably a function of oil weight, condition, temperature and clearance, so different in every case.

Dan

Frankie the Fink

MikeM

Yes, and you could have kept quiet and saved time off everyone's life that ready your objections to a non-issue. No disrepect to your opinion of course.

vettsplit 63

Frankie, the big block in question had been rebuilt- twice- by a shop out of the area, only to have oil starvation problems immediately. They had put a spin on adaptor on an early canister type block. The shop I use rebuilt the engine for the guy, and put plenty of clearance in the crank, only to have the same issue showing up in a filter that they use on the dyno ( they can look at any metal showing up) . They were having the same issue, and on a hunch, used an air file to enlarge the oil supply holes on the adaptor. Put new bearings in it again, and fired it up. That fixed it. The customer has had it in his Chevelle now for about 8 months, and zero problems.

Frankie the Fink

So some unknown amount of fuel in the oil can cause some unknown (but no doubt serious) amount of engine damage.....

I don't care what my dipstick or nose says; I'm spending the $25 for the oil change...and will keep advising people with this problem to do the same.

You don't have to be rolling in money to make good common sense decisions...

DansYellow66

Couldn't believe this thread is still going on. One concern I would have about any significant gas contaminating the oil is if you have a flat tappet cam. They need good oil protection to prevent loss of a lobe or lifter and for that reason when leaking carb gaskets recently deposited a significant amount of gas in my intake, I dumped the oil and replaced it while I was rebuilding the carb. Just my 2 cents - others may think it's not an issue.