The Stovebolt Site Forums The Shop Area General Truck Talk Molybdenum Disulphide

I saw a show on TV that mentioned 'Molybdenum Disulphide', an additive in some specialty oils and grease products. Has anyone here ever used this in their old truck? If so, was it oil or grease? Did it do any good? And lastly, where would I find it (brand names)? Thanks in advance.

Rance

That is the tech name for what is commonly referred to as Moly. It is a very common lubricant today. I have seen it in greases and spray lubricants, but I am not sure if I have seen it in motor oil.(I don't read the ingredients... if they are even listed)

Yes, some motor oils have it also. There is a warning in the Goldwing manual to not use an oil with it because it will make the wet clutch slip.

I'm the CFO at a specialty lube manufacturer and the owner of a 61 truck. We manufacture a number of products that contain Moly and I've had numerous conversations about what to use and not use in my truck with our technical people. Their advice to me was ... greases are good, but don't use engine oil with moly in an old truck.

I agree! There used to be a product called "slip" that was Moly in a kerosene-type solvent suspension. When it was added to gear oil, the solvent evaporated and the moly dispersed itself through the lube. Moly penetrates the microscopic pores in the metal, which makes the metal somewhat self-lubricating. Another use for it is as a coating for rifle bullets, which supposedly increases the velocity and accuracy. Use it in manual transmissions and rear axles, but not in engines or automatic transmissions.
Jerry

Phillip, if you don't mind me asking, what is the name of the lube manufacturer that you work for?

Also, moly is used on bullets to reduce the friction between the bullet and the barrel.

Phil

Originally it was sold by GM to be used in limited slip differentials to make them slip. In the early years the technology was not as good as it became and many times the plates would stick and if it became bad enough it was almost impossible to steer around a corner. Both axles would want to turn at the same speed as if you had no differential. One tube of GM Moly Lube (moliybedinum dissulphide) and voila all fixed.

we use it to lubricate the M242 chaingun
good stuff

Why would you not use it in the engine?

It's probably fine in modern engines and heavy duty (truck) use, but it's not good in motorcycles with "wet" clutches where the clutch runs in crankcase oil. It may not be the best idea in old engines either, although I don't know the reason. Perhaps the old type seals aren't good at dealing with it or it may cause sludging in high mile or non-pressure lubricated engines.

Some one else may be able to say exactly why.

Phil - My company is Southwestern Petroleum Corp in Fort Worth Texas. We've been around since 1933 and our market is commercial and industrial ... although there are a number of sports car and race car owners who use our products due to their high quality. We don't sell through retail outlets, but rather through sales reps directly to the end consumer. Phillip

We used to use "moly-b" when I was working on helicopters in the Navy, way back when men were men, the sheep were nervous, and the ships made of wood.

I still have a can of grease around somewhere.

Among it's other properties is that it doesn't absorb water, has a high viscosity, and a high tackiness. It's great stuff, but pretty pricy unless you're doing really bad things to your old truck.

Speaking of that, it's not that Moly-b is so bad for your engine, it's that synthetic oil itself can cause problems, depending upon the age and mileage of your beast of burden.

The trouble usually comes about when switching an OLD (high mileage) engine to synthetic is that it can actually CLEAN AWAY the crud and deposits that have built up on seals, causing them to leak. Putting in regular oil after that will also tend to leak out. This is why you sometimes hear about synthetics causing leaks. It's not actually the oil itself that's the problem, but the seal was worn, but the crud prevented the leak.

Of course, you can get the same effect by running your engine too rich (when your eyes water from the exhaust, it's probably too rich), or from using a detergent oil in your engine and not changing it often enough. Personally, I don't like detergent oils, period.

As an general rule-of-thumb, if you've got over about 10k miles on your engine, stick with the oil you've been using. If you do switch to synthetic, don't switch back.

You just know that there's always gonna be somebody out there who'll go "shoot, I switched to Mobil 1 (or similar) at 50,000 miles and never had a lick of problems! That guy don't know what he's talking about!"

The exception neither proves nor disproves the rule (of thumb) is all I'm saying.

My opinion, your mileage may vary.

napa has a grease in a spray can with moly in it called "open gear lube". i use it on all kinds of things. a good property of moly is that heat won't burn it off. like on a head pipe stud on an exhaust manifold outlet. wheel studs is another good place.
robert.