ATF is a great cleaner. Mix it with equal parts of acetone for a homemade penetrating oil. I have also added a quart to a slugged up engine, ran it for 1,000 miles before an oil change with amazing results. I did this with a ‘65 Chevy van with either a 230 or 250 (can’t remember) and a ‘77 V-8 non stovebolt that sounds like creep. In both cases it cleaned them enough to stop the lifter noises.
