Gentlemen, does anybody has an opinion,experience on using MoS2 based lubrificants(Molykote,Liquimoly,Loctite,etc.) on glow engines.Separately on bearings, cylinder or mixing in fuel? Any harm could be possible?

The biggest danger most likely be the moly could coat the platinum on the glow plug element and prevent the plug from working?

Enjoy,

Jim

MoS2 is commonly use as "Break-in" lubricant of a new cam shaft. Under load it breaks down into metallic molybdenum and crystalline sulphur. The sulphur crystals act as a polishing compound to speed the mating of the surfaces, the moly "Slicks" them up for long service life.

If MoS2 additives are used in small quantities in the engines lube oil they wont hurt anything, but their efficacy in this application is not proven. Other than the cam followers and piston rings the pressures and temperatures do not normally get high enough to cause the break down into the component metals.

Overuse does have dangers though. the MoS2 is particulate, not a liquid, and it tends to settle inside the oil ways, restricting the flow of the normal lubricating oil. I learned this the hard (expensive) way.

If used as an assembly lube in a model engine it probably wouldn't hurt anything, but it would make a mess on your bench. If you want to use it, a more sensible source would be a product like "Nevr-Seez" compound, as it is in the form of a MoS2 grease, rather than an oil. Still, I would use it only on the cam lobes and the faces of the tappets.

I would not consider adding it to the fuel, as its sludging tendencies could clog the carb ports and fuel lines.

Hope this is some help.

Bill.

Also as Jim said - the molybdenum could kill the glow plug. Forgot about that, thanks Jim.

Bill.

Thanks for your detailed concern on subject.I could see the problems with fuel mix, but isnt it be useful on ball bearings if used very careful on ball bearings(bushings too) maybe once in a season?.I can see some MoS grease available up to 392F (200 C). Maybe applying carefully on sleeve and piston before break in,helps longer life.
May I ask a little off topic question since I see u experienced on subject?What is your opinion Bill on adding some MoS2 to car engine(turbo diesel) high quality lube oil( syntetic)? Can it be harmful on some systems?Or maybe oil filter collects all and restricts flow?
Asking mainly because I have suffered an engine got slack only after 35.000 miles.(VW 1.9 turbo diesel)

Turk:

As I said, the MoS2 oils have not been proven to help in the normal running of an engine. Yes, since it's particulate a good oil filter will trap the MoS2, leading to the filter bypass opening. This gives a drop in oil pressure all by itself, and of course the filter does nothing after it clogs up.

I will not use it for anything except break-in lube on a new cam in a piston engine. And even then, not on a roller cam.

Really don't thnk the moly would have helped keep your VW rrunning - if it was run out in 35K miles there was definitely something wrong. Most likely somebody ran the pooh out of it.

Bill.

Moly is a no-no in ball bearings as it is a solid. It will take up running clearances and provide a bumpy road for the balls. It is great for any sliding surfaces and all that's needed is care. I once assembled a car engine with the dry spray version and got too much of it in the wrong places and I couldn't turn the engine over, so I had to disassemble and start over. I worked for a distributor of the stuff about 40years ago and sat thru several sales classes on it.

Thank u guys.