The Stovebolt Site Forums The Shop Area Engine Shop Crankcase full of gasoline.

So, this morning I drained 2 gallons of oily gasoline out of the crankcase of my jeep.
Somebody told me to put a couple quarts of ATF in there and spin the engine for a while, then drain it out and pour in the new oil.
Ever heard of that?

I guess the diaphragm on the mechanical fuel pump has a hole in it.

I don't know what good the ATF would do that oil wouldn't do better. Any gas that leaked in should have been in the pan. You've already drained that. If it was me, assuming the gas leak has been fixed, I'd just fill it with oil as usual and drive it. If it had been run with the diluted oil I'd let it idle for a few minutes to make sure everything had a coat of good oil before heading out.

I would just change the oil. Gasoline doesn't stick to anything, it all came out when you drained it. Water is a different matter.

Change the fuel pump, change the oil & filter, and do another oil change in about 500 miles. ATF has NO place inside an engine. If the engine was run with the gas-contaminated oil in it, it's already gotten enough of a solvent cleaning, which is what the dummies who reccimend an ATF flush believe will happen. The friction enhancers and various other additives in the ATF really don't need to be in an engine.
Jerry

Come on now... I for one like the look of the pretty smoke you get at start-up! :rolleyes:

I concur, no ATF in the engine. It contains friction material that could and would harm soft bearing surfaces. The gasoline has already cleaned your engines' insides, just pull the drain plug and let it drain overnight. The leftover gas will evaporate once you start driving and heating things up. For peace of mind, do an earlier than normal oil change as Jerry has mentioned,
Scott

What is this friction thing in ATF that is so horrid in an engine. I thought the operating temps, complexity and super tight running clearances in a modern computer controlled transmission made a engine environment a cake walk for ATF...and don't forget all those WC T-5 trannies.

Dummie-Stuart

Mercon ATF (Ford type) has an additive in it I was told years ago. ATF is designed to help friction materials grab one another where oil is to help them slip. It's not extreme but more coarse than engine oil. This is probably why the mythe started in the first place, thinking it would clean carboned up engines.
Scott

ATF has friction enhancers that allow the fiber and steel clutch plates to get a good grab on each other to prevent or reduce slippage. Every part in an engine needs a slippery lubricating film between the parts to prevent wear. When the spark plug fires and places like the connecting rod bearings, piston skirts, etc. get heavy thrust loads, tha absolute last thing they need is an additive in the lubricant that makes the parts try to stick together. How about the extreme shear force the lube film gets between a camshaft love and the bottom of the valve lifter? With a physical thickness about the same as SAE 5 oil, the ATF just doesn't have the viscosity to cushion parts in an old stovebolt designed to run with SAE 30 oil.
Jerry

Edit:
Scott, the myth goes back a lot further than Type F. Way back in the early 50's, when Type A, Suffix A fluid contained sperm whale oil, the idea was that it would clean up sticky hydraulic valve lifters. That didn't work, either!
Jerry

I just don't get the point of using other stuff, I knew a fella who put a quart of ATF in his gas tank every fill up, he also did the ATF in the oil flush occasionally & pired it down the carb to lube sticky lifters(never figgered out how it got from the intake down to the lifter valley, seems it would go thru the cylinders to me?)-his stuff didn't last any longer or run any better than mine using plain oil & gas. HRL is right, that engine is about as clean as it will get w/the gasoline going thru it.

I think a term is being misapplied. ATF has 'friction modifiers' in them, not 'friction enhancers'. This means the oil is compounded to react in a predicable manner in the friction area between clutches and plates (?). I don't know the chemistry of the additives, but it certainly could mean they allow extra slip as opposed to less slip.

Oil stock destined to become ATF is one of the highest cuts of base there is. When you combine this with the high performance additives, you end up with a 'super oil'. The modern automatic transmission is the most hostile environment on the whole car. It has friction and heat, ball bearings, bushings and sliding valves. One oil has to accommodate all these concerns.

I can't imagine that anything is put into this oil to increase friction, but I'm not a fuel and lube engineer.

Stuart

Type 3 ATF is commonly used in modern manual transmissions,some of them behind Vipers and Z06 Vettes.
A long time ago my daughter's car,a 70's Ford V-8 auto,started leaking red tranny oil from the front of the trans.I figured it was the front seal,pulled the transmission,replaced the seal.It still leaked red oil,must be the convertor? Not so,her well meaning boy friend had changed the oil for her,he was car dumb and used ATF by mistake unknown to me.The engine started to knock shortly afterwards,so before pulling the pan I drained the oil...RED!!!The engine was spotless inside,the bearings were also spotless,especially where the bearing material was worn to the bearing shell.

Bummer on that stupidity Fast Truck !

The only time I've used ATF in an engine was when one was siezed up with rust. Poured some in each cylinder, let it sit a few days and try to turn the engine over. Works fair in one that's not too rusted up and you're planning on overhauling anyway.

I think the rumor started because of the huge amounts of detergent present in ATF.

There are detergent boosters available over the counter, but the only "snake oil" I would add is Marvel Mystery- it really does do things for lifters and sticky valves. But, if there isn't a problem, I don't add anything but high quality oil to my crankcase.

Any damage done by the gasoline isn't going to be reversed by anything you can add, and any gasoline that was in there is gone.

Besides, Willys engines are tough, I'm sure its fine.

Stuart,
I'll bet you if you filled an automatic trans with plain engine oil, it wouldn't make it 20 miles before it burned itself up from internal slipping,
Scott

Gas in the oil won't harm the engine... As long as you let it warm up slowly, and idle for a while.

Northern aircraft operators had special valves added to the fuel/oil system to pump gas into the sump prior to shutting down. The dilution was timed, and the "boil-off" time was charted based on the time it took to dilute the oil and the outside air temperature. This system allowed a lightweight aircraft battery to turn over a large engine in cold weather. Taking off too soon led to foaming oil sucked out of the breather, and subsequent low oil pressure.

What HYFLYER said. Oil dilution systems in aircraft engines are very common in cold climates especially the big radials. Weeds

find the reason for the gas change oil and drive the heat will get any left over gas out just like water in the oil the heat from running the motor will get it gone

in the old days around here if your motor was dirty inside you would pour a qt. of atf in a week before you change the oil it would clean the motor out but today the oil its self keeps your motor clean if you change it often inuff in my barn i have a barrle of none detergent oil left over from the war its thick stuff i would not use it in a motor but thats what they had back then