I have used fuel additives on occasion during my 63 years of driving. Does that make me an expert? Of course not. I think the reading I've done has provided me with more knowledge.

Here is a classic from another forum,

"During WWII, mechanics used Marvel Mystery Oil in rotary engines by the 55-gallon drums full. They claimed it saved many a engine from sticking valves. I used it in my airplane engine with the same results, never a stuck valve since I bought it in '83. Others that I know have had valves stick that did not use it. With that, I've used it in all my auto engines as well, and occasionally add it to the fuel."

This caught my eye because my father used Marvel Mystery Oil in his shop before I was born. And it has been offered in 55 gal. drums, but it wasn't used in rotary engines during WWII. That engine wasn't invented until the '50s. No doubt, "... it saved many a engine from sticking valves." The rotary engine has no valves. Well, to give the author credit, he may have been thinking of another engine.

So what of all these other additives? I think it can be best summed up by another post,

"After reading responses to date, I have a hypothesis - I think its kinda like religion, if you believe it, it is absolutely worth it. After all, where can you put down a few bucks and get a good feeling about (possibly) doing good.."

You say,"But look at all of the studies that have been made." No doubt made by laboratories paid for by the manufacturer. Think - diet pills. They all get glowing reports, because we wouldn't see the reports otherwise.

Nothing I write will change the mind of a believer, but I hope it might prompt some thought from the person who is wondering if a fuel additive is worth it. On the other hand, most of them are inexpensive and after diluted to a .008% solution (12 oz in 12 gal. gas) it could hardly do any harm.

I'm sure many will disagree with this. I am more curious to see if there are some who will agree.

Cheers

 

I'm sure they are referring to "radial" engines, which do have pistons, valves, etc.

Jim

 

Been using both Prestone's FI cleaner and Chevron/Techron. Usually one bottle to
full tank every 15K miles.

Intake manifold was removed while in the area doing some work and the valves were mirror shiny like new at 115K miles......

As far a MMO goes. Used it in an old Chevy we had but really feel no need to dump it into my MINI. I usually go 5-7K miles for oil changes and use Amsoil.

 

They used rotary engines on aircraft in World War I. http://en.wikipedia.org/wiki/Gnome_Monosoupape

Not the same rotary that you're thinking of--but it was called the same thing.

I'm sure the report meant "radial engines", like these: http://en.wikipedia.org/wiki/Pratt_%26_Whitney_R-4360

My grandfather built a special setup to squirt MMO onto the back side of the exhaust valves in the little Lycoming twin in his Aerocoupe. Those engines had problems burning exhaust valves, but a little bit of MMO helped prevent that. It probably also helped with valve stem lubrication.

He never ran it in the fuel system, this was a separate little spray-bar that either sprayed or (more likely) dribbled the oil onto the valve.



...That all said, I wouldn't put MMO in my MINI's engine. It's not air-cooled, nor is it known for burning exhaust valves that I have heard. I may run some injector cleaner periodically, but maybe not. And oil additives? No way no how.