I have heard that one before. I use it on my engines that have alot of miles before an oil change. I dump a quart in let it warm up, drain it and do the filter and oil. An old school guy years ago told me about it. Cleans the inside of the engine very well.............and no I aint lyinnnnnnnnnnnn
So the guy at the auto parts store I do not think is that KRAZZZZZIEEE!!
My opinion of course
I used Deisel oil called Delo on my last break in. Worked great with flat tappet cam.