oil dilution
 

I have about 50 mi on my 15/40w rotella break-in oil. The weber carbs have flooded on shut-down (boiled) and diluted the oil to some unknown degree. Should I dump it or run it ? Oil pressure is within Shelby specs, but is 80 lbs only when cold, drops down as soon as it's warm, but within specs.
I would think the gasoline in the oil would evaporate/burn away with use.
What say you?

Uhhh, I would change the oil.:JEKYLHYDE And unless you have a solid flat tappet cam, whatever oil you choose is not going to make a huge difference so long as it's decent.

Change it before you run it. Gasoline will mix with the oil and thin it out. Tom

Change it....

Hmmm, if you have a jar full of motor oil, and you pour in half again of gas, will they mix or separate?%/

Doesn't matter......an oil pump will pump it all and then you get etched bearings and washed down cylinders. :)

That's no answer.:LOL: Do you know whether it will mix or separate? And if it separates, which goes to the top? Of course you do know that it is not unusual to have the presence of fuel in your oil analysis. Levels of 2%, according to my Blackstone reports, are not considered out of the ordinary.%/

check the damn dipstick.....is the level considerably higher?
if no then the amount of fuel in there is insignificant. run it warm for a half hour or so and it will have turned to a gas(fumes) and have been purged by the breather or PCV

i see alot of folks here thinking they are ken miles doing racing research. its a street motor for gods sake.

Or just use the old "match stick" test. Wave the lit match at the top of the open dipstick tube and, if nothing untoward occurs, you're good to go....:cool:

I would change it even if it doesn't have a lot of gas in it. The oil is a lot cheaper than taking a chance with an expensive engine and a whole lot easier to replace. But on the other hand I change my oil a lot more often than most people and it really doesn't have to be changed that often. I just prefer to err on the side of caution.

Ron ;)

Have fun keeping those webers from boiling over after shutdown. Let me know when you discover a cure.
Any day over 80 deg. F, I leave the hood up and the coolant fan running for awhile after shutdown. Good luck, Wolfgang

Here is your answer. Yes oil and gasoline mix and do not separate. We do it all the time for the old 2 cycle engines.

My son built a SBC. The new mechanical fuel pump had a hole in the diaphragm, unbeknownst to him. After the normal start up set timing, etc. it started to knock at idle. He called me to come listen to it. Car had an idiot light and it never came on. I said check the oil. He said I just poured 5 quarts in, I know it is right. I said humor me, I'm old. He pulled the dipstick out and it was about 4 quarts over, thin as water, and smelled like gasoline.

Bottom line it was well mixed and never separated, when the engine was pulled apart a week later.

Good nugget of info that I did not know. Thanks.

It may be a little known fact, that during WWll (and other times) aircraft piston engines used in very cold climates called for dilution of the oil with fuel to aid cold starting. I don't know the percentage of fuel used, but I'm sure it was small, and the fuel vaporized out as the engine warmed up. You can Google it for more info. The point is that a small amount of fuel in the oil is tolerable, but not worth the chance under normal circumstances.

Back when I was a puppy, the old dogs of that time advised you could add a quart of kerosene into you oil to clean sludge out. I did that several times with junk yard engines and used cars I picked up cheaply. I would let them idle about 15 minutes and then change the oil.

One particularly sludged up 283, I put in a Vega (I was building a 327 to put in it later), I added Kerosene and decided to leave it in to soak and clean until the build was done. I just started it to move it once in a while. After I finished the car, I forgot about the Kerosene and drove it around town for a day - maybe 50 miles. I destroyed the rear end on the way home. When it let loose, the engine likely hit 10K on a free rev (pegged an 8K tach). The engine seemed fine after that. I sold the engine to a friend who sold it to someone else who planned to rebuild it. The guy claimed all 8 rod bearings were spun. I always doubted it, as it ran just fine when I pulled it, but I will never know for sure. Bottom line, if you do try this trick. Let it idle a bit and then change the oil immediately. Don't repeat my stupid stunt.

PS
The guy did say the engine was clean as a new one. I had changed the intake, and it was hideously covered in sludge, so the Kerosene does clean them up. Wonder where it all went? Through the bearings?

I had an uncle who I heard used kerosene as a sub for antifreeze.

I did have a 15hp kaw engine on my mower that suffered oil dilution from fuel that I didn't know at the time, though the oil level was suspiciously higher than normal. Two lawn mowing trips later the rings were shot, couldn't get it to run without ether and the choke had to be used to keep it running. result--toasted engine.

Oil Dilution
 

change the oil its not expensive, and then you dont have to play head games.

I know several people who have found the gas tank empty and the crank case full of the missing fuel. The needle valve will leak fuel and it runs down the intake valve guide. A quick fix is to put a shut off valve in the fuel line and always close it before you shut it off. You don't have to run it dry, just a tad low.

There used to be a product on the market, might still be for all I know,it was for engines that see a lot of"city" driving and/or older gummed up engines,I used it once on my grandmothers car...This car had 50,000 miles on and probably never went past 3000 rpms,in her old age (90's) she only drove in town and averaged about 3000 miles a year....the car had a hard time getting much past 45 mph!!!!!!
Anyway,the directions said to get the car to operating temp for at least 10 minutes, pour the one quart stuff in the crankcase and let idle for 15 minutes, then change the oil and filter......it was supposed to help dissovle the sludge in the engine......
On the label it stated it was 95% kerosene,5% petroleum disstilates......it did seem to work though......
An old mechanic told me they used kerosene to flush the crankcase on engines that went under water....they would pulled the plugs and crank it over to get the water out of the cylinders and then pour in 4 or 5 quarts of kerosene after draining the oil, then remove the coil wire and crank the engine over for about 20 seconds and then drain the crankcase, then refill with oil,crank the engine with the coil wire off and spark plugs out till it built up oil pressure, then put the plugs in and start it and let it go.........

It has always been a real headache for bikers with carbs.The gravity fed fuel mixers with leaking needle seats are famous for loading the cylinders with fuel.Anything gavity fed can suffer that fate.
I too would change the oil 50 miles is enough for the breakin oil.