molybdenum disulfide

[Gundy]

Anybody ever used this stuff as an oil additive?

I have a friend who swears by it. Thinking of adding it to
my 250K and counting Benz's motor. He suggests a couple of tablespoons to the oil.

Thoughts...experiences?

 

[TR3driver]

I like MoS2, use it in several different ways. It's a great dry lubricant; and withstands high pressures and temperatures.

But motor oil doesn't operate at those kind of temperatures and pressures, nor is it dry. It takes years of study to learn to formulate motor oil, it's a complicated mixture of many different chemicals in just the right proportions. And both the list of chemicals and the proportions vary not only among brands but among individual formulations within brands (for example, Valvoline Racing is significantly different than Valvoline MaxLife). The idea that you can "improve" every motor oil by throwing some more additive into it just seems counter-intuitive to me.

So I would rather start with a quality oil, designed by professional tribologists, and not try to re-engineer it on my own. YMMV and all that.

 

[Gundy]

I use Castrol 20-50 in the old girl. I've never been one to add mystery snake oil to my engines/tranny etc.
I like synthetic for some applications as well.
I'm just trying to get a little more life out of the trusty old Benz and he suggested this might help.

Could adding a couple of tablespoons of MoS2 to 8 quarts hurt?

He thought it was used in WW2 German planes to extend running when fluids were lost and had been added to the oil.

The old 420 SEL runs great and is in great shape...but...250K
is still 250K.

 

[TR3driver]

Well, not strictly comparable; but in a moment of weakness, I tried some Marvel Mystery Oil in the crankcase of a Chevy pushrod V6 with some 250,000 on the clock. That particular engine was known for having a weak crankshaft, but I had used it hard for over 20 years (including towing a TR3 on a trailer some 2000 miles) and never had a problem until I tried an additive ... less than 1000 miles later, the crankshaft snapped. Just rolling down the road too, not any unusual load or rpm at the time. <span style="font-weight: bold">Bang</span>.

Could be coincidence, but I don't care to repeat the experiment. It's replacement (Chevy pushrod V8) has some 230,000 on it so far, and after a brief misadventure with Mobil 1, I am going to be sure it gets nothing but a steady diet of the Valvoline full synthetic that it's used to.

Your WWII anecdote might well be true; but I daresay that today's oils are a whole lot different than what they had 70 years ago, plus I'm hoping to get a whole lot more than 100 missions out of my engine. Supposedly MoS2 additives have a tendency to create sludge (the MoS2 doesn't dissolve and slowly falls out of suspension), which isn't particularly a problem in an engine that is torn down and cleaned regularly; but might be more of an issue if you aren't planning on a periodic teardown (as is required for aircraft engines).

But still, this is just my $.002 worth. I haven't actually tried the moly (and I'm not going to).

 

[PAUL161]

Molybdenum is great in greases. We used moly enriched products for years, but only in the grease line, never in motor oils! I've seen moly under a microscope and the true moly has microscopic beads in it. I'd be very cautious about putting a product with it in it, in an engine. It will take a tremendous amount of heat. The Navy used it to lubricate the afterburner controls and slats on jet fighters for some time.

 

[Gundy]

Well, I added about 2 tablespoons to the old Benz.
I have to say the engine is quieter. Almost like
it was back in the day. This morning the wife asked if
the motor was running when she got in. It's been a while
since that happened.
It may ruin the engine. But what the hey, the old girl is rapidly approaching 300K.
If she blows or seizes....guess the wife gets her a new one.

 

[texas_bugeye]

Molybdenum is great in greases. We used moly enriched products for years, but only in the grease line, never in motor oils! I've seen moly under a microscope and the true moly has microscopic beads in it. I'd be very cautious about putting a product with it in it, in an engine. It will take a tremendous amount of heat. The Navy used it to lubricate the afterburner controls and slats on jet fighters for some time.

My Father inlaw worked for Eastern airlines in Miami with the airbus simulators.
They had problems with wearing out joint's and cylinder anchors. They swithched to a Molybdeenum grease and the problem was "gone" it works great in high pressure appications.

 

[Hap Waldrop]

David, just don't use it on the cylinder walls of a new rebuild, I hear that doesn't work too well

 

[Gundy]

David, just don't use it on the cylinder walls of a new rebuild, I hear that doesn't work too well

Oh I know that tale! The old Benz is a little quieter and
MAYBE this will chill the wife's desire for a new S Class.
For a while anyway. (crossing fingers and toes)
'Cause we all know : What Momma wants....Momma gets.
Trick is to steer the desires.

 

[Cottontop]

Back in the mid-60s, I owned a 1963 Pontiac Tempest HO. The car had a 326 V8 and a 3 speed transmission IN THE REAR.

1963 is the year that Pontiac "balanced" the Tempest driveline and had the engine in the front and the unit transmission and rear end in the rear.

The driveshaft was a long 1/2 inch solid rod and was 3 inches lower in the center than on both ends. That arrangement gave a flat, no hump, floor.

The unit trans and rear end had a TERRIBLE, LOUD, whine in low and reverse. I added about 1/2 cup of Moly DiSulfide to the gear grease. The whine never went away, but it was less than 1/2 as loud as it was.

I'm a believer and still use the stuff in my transmissions and non-posi rear ends. It's in my Healey.

Tim

 

[Gundy]

Tim,
I loved those Tempest! GTO before there was a GTO.
BAD to the bone. I had a friend who had one back in the day.
White. It would squat and GO! Light car with a powerful engine.

 

[Cottontop]

Gundy,

Mine was a maroon convertible with a maroon interior and a white top. It was indeed a runner and an all around good car, not a GREAT car, but a good car.

I traded it in on a GREAT car. My very first BRAND NEW car. A 1967 GTO. 400 Cubes with a turbohydro and special ordered bench seat (NO buckets for "sweetie" or me). That is one I wish I still had.

Tim

 

[Mychael]

I've been adding Moly Oil to my 1995 1.3 litre Nissan since new. Every engine oil change (10,000K). Car has now done 366,000k and still uses no oil between services.

In my previous TR3A I added Nulon to the engine oil, actually did the full Nulon treatment package, this was an old engine but it did run a little cooler after the treatment.

 

[BRSLimited]

Well, not strictly comparable; but in a moment of weakness, I tried some Marvel Mystery Oil in the crankcase of a Chevy pushrod V6 with some 250,000 on the clock. That particular engine was known for having a weak crankshaft, but I had used it hard for over 20 years (including towing a TR3 on a trailer some 2000 miles) and never had a problem until I tried an additive ... less than 1000 miles later, the crankshaft snapped. Just rolling down the road too, not any unusual load or rpm at the time. <span style="font-weight: bold">Bang</span>.

Could be coincidence, but I don't care to repeat the experiment. It's replacement (Chevy pushrod V8) has some 230,000 on it so far, and after a brief misadventure with Mobil 1, I am going to be sure it gets nothing but a steady diet of the Valvoline full synthetic that it's used to.

Your WWII anecdote might well be true; but I daresay that today's oils are a whole lot different than what they had 70 years ago, plus I'm hoping to get a whole lot more than 100 missions out of my engine. Supposedly MoS2 additives have a tendency to create sludge (the MoS2 doesn't dissolve and slowly falls out of suspension), which isn't particularly a problem in an engine that is torn down and cleaned regularly; but might be more of an issue if you aren't planning on a periodic teardown (as is required for aircraft engines).

But still, this is just my $.002 worth. I haven't actually tried the moly (and I'm not going to).

I have had the same problem with Marvel Mystery oil. Put it in an engine that had some sludge buildup, within 1000 miles the engine is dead. I know of at least 3 other engines that have done it too. IMO if additives were so great why don't they recommend them from the factory. I was told by the developer of slick 50 that the best oil you can buy is the cheapest you can get that meets federal specs.