Whats that noise coming from my 318?

RustyRatRod said
Because that's specifically what it's made for. To get into the lifters and help free them up. It does not work every single time, but it does a lot. It's a cheap try before having to tear into the engine.

It also serves another purpose,,

If the noise hadn't gone away and the lifters needed removal,, you'll find the Mystery Oil has desolved most of the varnish build up at the bottom of the lifter,, making them easier to remove from the bore..

They often come out with just a magnet,, saving having to use the lifter "slide-hammer" removal tool..

hope it helps