Using transmission fluid to clean an engine.

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I heard from someone, who works on older cars (especially ones that have sat idle for months and even years), a technique he uses for cleaning "sticky and/or ticking lifters".

He told me to add a quart of "Dexron/Mercon III automatic transmission fluid", to the existing engine oil. Then, he says to let the engine idle until it has reached its normal operating temperature. Then, you drain the oil, with the ATF in it, and replace the oil and filter with new.

He said the ATF won't hurt the engine (especially the bearings, like some motor flush products can) and the "detergent power" does a good job of cleaning.

Does this sound like it would work and not cause harm?

Any opinions?
 
I believe that even though widespread, and often utilized, this is a myth that should be abolished.
There are no detergents in ATF, so no magic properties. Adding any very light oil would do the same - that is, a tiny bit of flushing occurring.
 
just another one of those old wife's tale.

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p.s. I used to do small import engine blueprinting and repairs for SCCA racing.
 
ATF is more or less a hydraulic fluid. Putting in the engine will do nothing.

I use synthetic ATF in the hydraulic system on my Western snow plow.
 
The only way I've seen this help is to literally pour it down the throat of an Olds 350/2bbl we had, via a leaky transmission vaccuum modulator. Sucked 5 qts thru before we figured out why we were fogging mosquitos everywhere we went, and why the car ran like a 3 legged camel in a swamp....

Purely by accident but it sure ran smoother than it had in years.
 
This was common practice decades ago amoung gearheads. Back in the '80s, I had a '76 Mustang II that sludged up pretty badly. It was so bad that the oil ports going through/to the camshaft lobes were plugged. The car started screeching one morning - I popped of the head cover, opened up the ports by rodding them out with a thin wire, and the screeching disappeared. There was a film of gunk coating the entire engine.

Then I took the advice of a gearhead friend at work. I poured a quart of ATF in the crankcase, left it in there for 100 miles, and drained/replaced the oil & filter. I didn't have a problem with the car after that.

A few months later I parted out the car and sold the engine to another friend. He dropped the oilpan just to make sure that everything was OK, and he told me that the engine and pan were spotless.

Yes, ATF fluids have significant amounts of detergents. I can't say if this is a good practice on today's engines, but experience tells me that it definitely works. And since many engine flushes contain large amounts of kerosene, I'd think that ATF is likely better for your engine.
 
Does not work! ATF does not have 1/5 the additives of plain jane motor oil. The base stock in most cases is old school parrifin based group I. Nothing magical about ATF. It is an old wives tale. If you have rusted parts use a penatrent like PB Blaster, Mouse Milk, Kroil, Pentro 90 etc...If you need to clean sludge use 131,Auto-Rx, Lube Control,Amsoil flush, B-12. Some of these are better then others. Some are better on sludge and some are better on varnish.
 
I think the only feature that was ever present in ATF for this use was as a viscosity reducer. The stuff goes from a 10 weight to a 5 weight in normal use (if I read the UOA vs. VOA on them). So you probalbly got some goo to flow out of the engine when you changed it.

This was a factory recommended add for some SBC to reduce lifter noise in certain years. This, I think, is where the practice gained mythical credibiltiy.
 
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