Marvel Mystery Oil debuted back in 1923, developed by Burt Pierce, but according to one story, the oil’s name came from a question from someone, asking what kind of oil it’s supposed to be, and Pierce answered back, “It’s a mystery”. Well, today it’s known that this mystery oil is comprised of 75% mineral oil, 25% turpentine-type stoddard solvent and 1% lard. And even though this formula was developed back after WWI it still has a loyal following today because it increases power in engines reducing blow-by and keeps carburetors clean. Marvel Mystery oil can be added to both gas and engine oil, with proven benefits including more power and much longer engine life. However, in motorcycles with a wet clutch, it’s not recommended to add to the oil because it may cause the clutch to slip as these type of transmissions rely on some friction. Synthetic motorcycle oils do not contain the same sort of friction modifiers that automobile oil has, so you never want to use automobile oil in wet clutch motorcycles because these friction modifiers could result in clutch slippage. But, in the gas of a bike, it’s better than just fine to use.
One huge problem for modern day engines is the use of lead-free gasolines, and despite the use of hardened valves, there is no good top end valve and upper cylinder lubrication for modern engines. Marvel Mystery oil will keep newer engines together longer by reducing wear and providing more power by providing this top end lubrication to modern engines. This top end lubrication could make some newer engines have double the life of other newer engines that don’t use Marvel Mystery Oil in some cases.
Old time car guys and motorcycle guys still know about the benefits of Marvel Mystery Oil and love the stuff. It’s a proven fact. 90 years of satisfied motorheads is a good thing!