Marvel Mystery Oil53436 Original Motor Treatment, Add to Fuel & Oil for Superior Cleaning, Removes and Prevents Sludge Build Up and Leaks, Extends Oil Change Intervals and Mileage, 48 oz. (Pack of 2)

I've used this for at least 50 years. I use a 50/50 mix of MMO and Sta-bil in the fuel tank of everything I own that runs on gas. Vehicles, mowers, motocycles, equipment, etc. Keeps the fuel fresh and from sucking up atmospheric moisture that leads to poor combustion. I also add 8oz at every oil change in my all my 4 wheel vehicles. Everything runs much smoother than without, is more efficient and I've had the same Craftsman push mower for more than 15 years. I think this and Shell Rotella T6 motor oil are some of the best products out there for keeping your stuff running well and to last longer. Well worth the effort!

Great product

Marvel Mysterey oil was given to mankind by a benevolent, but, mysterious alien race. They used it as salad dressing and marinade; but for us, it is an amazing lubricant and fuel additive. I use this in oil and fuel. It is also a good cleaner (in certain circumstances) and smells great.

If you’ve never used MMO before, you will be surprised if added to your fuel. It’s a product you can actually “feel” a difference in how smoothly the engine will operate. Upper cylinders rarely get enough lubrication from motor oil alone & MMO preserves the valves & piston rings. It’s a simple way to make your engine run better for a long time. If you use conventional motor oil I’d use it in the crankcase too. Since I use synthetic motor oil I only use it for my fuel, but the engine purrs like a kitten.

Great additive since they stop making detergent oil. keeps engine clean and greatly reduces oil consumption from sticky piston rings and sludge buildup.

Marvel Mystery Oil was created in the 1920s. I’ve used their products since the ‘90s on older, high mileage vehicles, and the improvement is almost immediate. A little better mileage, smoother idle and it seems to get the gunk out in both the fuel system and the crankcase. These bottle a just a little clumsy to use,

I've a small farm and have collection of older cars, trucks, motorcycles and gaggle of gas powered equipment over the years. I HATE rebuilding carbs or cleaning/replacing injectors. Yes, I've watched all the videos on YouTube on additives. Many, many years ago after getting fed up I started adding MMO to "all" gas I buy. I use non-ethanol gas in everything which isn't in use often. Adding quality gas filters and shutoffs to equipment that came without. For vehicles and gas I don't use frequently quickly adding Ethanol Shield too. All I can say as an old guy with toys this combo has worked amazingly. I use good quality oil (now full synthetic) with excellent results. I cannot speak to MMO "fixing" existing issues performing rebuilds first when buying used.

Good product and price