Never been a fan of Chemical Magic fixes, but can testify that the 1/2 VW I fly behind on my Airbike began running rough, Did a leakdown test, 1 cylinder was down at least 40-50 pounds, drained off 1 qt, put in 1 qt MMO, it holds about 3 qts. w/cooler.
Jumped in her and flew around the patch just in case........... she started to smooth out so I left the pattern, put a little over an hour on it and landed.
There had been a huge argument between a few of the guys at the field about MMO and snake-oil in general...................Leakdown in both cylinders was just below 200 psi.
Made a believer outta me, don;t know if a guide was sticking or rings varnished up or both, I just know what the leak down said, Andy