Originally Posted By: bmwtechguy
You are right, no simple oil "additive" that I have tried has significantly raised compression long-term. I have, however, seen firsthand that the engine cleaner, Auto-Rx can significantly raise compression on a cylinder if the rings/grooves were dirty and rings partially stuck. The higher compression and resulting higher horsepower does not go away and certainly would not be considered a bandaid....the Restore stuff, OTOH.....I see that as more of a bandaid for a dying engine.
+1 There is a big word in your statement: IF. "If the rings/grooves are dirty or partially stuck". People have to understand a neglected engine, or one of unknown history might have mechanical issues way beyond the scope of an oil additive. It's these cases where a product will not work, no way, no how.