ATF in engine?

There are products on the market specifically made for flushing the crankcase. I have used Gunk™ for decades. When I pull the valve covers to adjust the valves, the heads are clean.

I've used ATF before with good results, but the results will depend as much on what kind of oil you use. The worst case I've ever seen was a friend of mines car years ago. He only used quaker state, and we had a reason to pull his valve cover off one day. I've NEVER seen so much crap on an engine in all my life! It was literally a 'frozen' waste land. Solid 'oil' all around the springs, with only enough clearance for the springs to move. It was amazing to me to see. If you use good oil, and change it fairly often, you shouldn't have any sludge anyway...

atf does work, so does diesel fuel. just remember to use a qt of regular engine oil at the same time for lubrication. you can also use marvel mystery oil as well. run the engine for 20 minutes at idle, then change the oil and filter.

be careful..........i bought a '68 f150 and one of the first things i did was change out the oil,,,,,what i din;t know was that previous owner didn't use detergent oil.................

next thing i know, the oil pump is clogged with crud, and i'm pulling the engine .............

I'd do it on a motor that is gummed up. However, I would pour in 1qt and drive for about 100miles before a filter and fluid change. Doubt you'll have to drop the pan, it's not a miracle just oil with more detergent in it.

That was an old trick that started back in the 1950s. You would add a quart of GM Type A ATF in place of 1 quart of oil at oil and filter change time to severely gunked-up engines because the ATF had a detergent additive (this was back in the days of non-detergent motor oils). Today you have good oils and a selection of high-detergent additives to select from.