Hello,
I have a never used O.S. 4 cycle that I keep a bit of marvel mystery oil in it to keep it oiled during storage. A fellow modeler told me that Marvel mystery oil destroys the diaphragms in 4 cycle engines.
I did a search of forums and cannot find anything like that. In fact, to the contrary, lots people seem to use it in both 2 and 4 cycle.
So what’s up?
Is this personal opinion or is there some truth to it? Truth, of course, being empirical evidence backed up by data. Not something like "me and another fella both had engines go bad and we both used Marvel oil, so I know it must have been the marvel mystery oil."
Let me know your thoughts

Glow engines with silicone pressure regulating diaphragms or other silicone fuel system components are susceptible to damage by petroleum oils. This includes YS engine, two or four stroke, and later model OS pumped engines. The manuals are very specific so this shouldn't be an issue. Silicone components swell when exposed to petroleum products and this interferes with their function.

Greg

If your engine has diaphragms in it, such as with a fuel pump and regulator then yes it is possible for MMO to damage the diaphragms. The silicon parts can be damaged by petroluem based products.

But if you have a regular 4 stroke engine without all the fancy widgets, then it is no problem. You can use MMO all you want to.

You should be using whale oil for ARO.

O.K., I read the manual complete.
It appears I should be ok.
The oil I added was through the exhaust port with a few flips now and then to keep the thing oiled and free moving. It should only be in the case, shaft and bearings. I doubt it ever got into the pump system since I never ran the engine or put oil in the carb system.
That's my thoughts at least.

Originally Posted by ronj10

O.K., I read the manual complete.
It appears I should be ok.
The oil I added was through the exhaust port with a few flips now and then to keep the thing oiled and free moving. It should only be in the case, shaft and bearings. I doubt it ever got into the pump system since I never ran the engine or put oil in the carb system.
That's my thoughts at least.

Saito 4 strokes, at least the one I have, advises adding ARO via the breather nipple and the silicone fuel tubing you typically have hanging down from it; I'm pretty sure most ARO has a petroleum based component (I use ATF).

Originally Posted by jsipprell

You should be using whale oil for ARO.

It's a renewable resource!

Originally Posted by ahrma_581

It's a renewable resource!

I'll bet the whale has a strong opinion about that.
lol

I prefer baby seal oil

Originally Posted by jsipprell

You should be using whale oil for ARO.

Northern hemispere whale oil or Southern hemispere whale oil?

I heard one is better for 2-strokes while the other is for 4-strokes, but I can't remember which..

That would be Northern Hemisphere for both 2 and 4 stroke, because the coriolis forces will make it turn CCW when going down a drain, and that coincides with the rotation direction of the crank....

It is the reversed rotation engines that need the Southern Hemisphere oil....

Tsssss, that you didn't know that....



Brgds, Bert

I won't dispute the experts here. But I use MMO, and I use silicone fuel tubing on the nozzle of my ARO bottle. It has MMO in droplet form resting inside the tubing. It has been in use for several years. I have never seen any degradation of the silicone tube.

G'day All,
I don't know what you are worried about, If you think about it, ARO, should be injected into the crankcase of 4 stroke engines, NOT through the carby, where the pump diaphram can be effected, It is no use going through the carby because the oil only goes to the head, & then it's expelled out the exhaust, & not into the crankcase as in 2 strokes, the bearings are in the crankcase & that's where the ARO is needed.
PS there will be enough blowby to lubricate the rockers & pushrods.

Cheers.
Allan.

Originally Posted by earlwb

If your engine has diaphragms in it, such as with a fuel pump and regulator then yes it is possible for MMO to damage the diaphragms. The silicon parts can be damaged by petroluem based products.

But if you have a regular 4 stroke engine without all the fancy widgets, then it is no problem. You can use MMO all you want to.

In the latest FS-91 S2-P engine manual OS states : fuel pump assembly, carburettor/pressure-regulator and silicone tubing must be cleansed separately in methanol or glow fuel. On no account must they come into contact with kerosene.......appropriate alternative may be one of the high-quality synthetic lubricating oils.

Bert-I live in North America-I counted the revolutions of expelled water through my sink trap...They were 17 RPM's .....Do you really think I'm going to lose/gain significant power ?
Ha Ha HA....Earl..