Adding Molybdenum disulfide to moder motor oil, is it worth?

Decades is the right word. Molyslip was that additive of choice for "performance" motorcycles in the mid 60's. It did little for Bantams, Cubs and C15's. It was questionable even then as a useful additive for Jap bikes, but if you had a Goldie, a clubman Bonnie or a Norton SS was more or less de rigour. My mate used it in his MGA twin cam and latterly in an Escort with a Broadspeed engine, but by the 90's with semi and full synthetic oils around for high performance engines it seemed a bit passe.

My son used Castrol Magnatec in his 15 year old Toyota Corolla from new and it's got 140k on the clock and still going strong, so my take on this is "No" modern lubricants are good enough and molly is now relegated to "snake oil" unless you have a classic.
 
Why would you want to do this?

If it ever worked for your a Goldie, clubman Bonnie or a Norton SS why did the oil manufacturers not know this when apparently untrained non-technical grease-covered youths riding them did? Or imagined they did. Go figure.

Why would "molly" only work on old engines and not on newer ones?That's not rational. Anyway I thought the experts said Morrison's straight 40 (etc) was the thing for oldies simply because it didn't carry any silly snake-oil.
 
If it is a boat engine then wear is not a problem. Small boat engines are very lightly stressed and only need the most basic oil. they are lifed between 8-10000 hours, reflecting their normal use in industrial applications. Yacht engines average 150-200 hours a year so typically last between 30-50 years.

The biggest enemy is lack or use, followed by running short periods at low power outputs. Best way to extend the life of your engine is to run it frequently under load at around 70% maximum and change the engine oil and filter every 100-150 hours or every year. My last boat was used like this as a charter boat and clocked up 3500 hours. Ran as good as new when I sold it.
 
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Its called progress. If you go back to the 1950's car and bike engines were built to standards that would be completely unacceptable today. Bearing clearances were bigger than on modern engines, and crucially surface finish was much worse. You changed oil very frequently and popular car engines had a pretty short life, with most being knackered well before 100,000 miles. Rebores and engine rebuilds were often carried out after far fewer miles. The result was that the snake oil salesmen came up with a number of "magic" concoctions claimed to extend engine life. Then two things changed. Firstly multigrade oils appeared, and the oil makers started putting additives in them. Secondly the engineering standards of engine makers improved, so now we have car engines that go for a year or more betwen oil changes, and have far longer service lives without major overhaul. My last two cars have never even needed a top up between oil changes.

As an example of how good engineering standards now are, and how much abuse a modern engine might withstand, my neighbour's wife bought a Citroen CI that had belonged to friends who were emigrating. The friends had bought it new, driven it 90,000 plus miles and had never had it serviced or changed or even topped up the oil. It still ran. What passed for oil looked more like poster paint and barely touched the bottom of the dipstick. After an oil change and a proper service its still going strong and the only sign of its abuse is a bit of tappet noise. A 1950's engine on 1950's oil would have been destroyed in less than 30,000 miles by such treatment, and probably much quicker as older engines used oil and needed regular topping up.
 
I remember buying a tube of gunge for my old landrover, if your engine smoked (as most did) you could squeeze the gunge into all 4 cylinders, it was marketed as an easy fix instead of a rebore, it was supposed to seal the cylinders and stop oil burning, i was one of the idiots that tried it, needless to say, it was snake oil, and expensive!
 
Molybdenum disulphide (or sulfide I suppose now) is a boundary lubricant, useful where hydrodynamic lubrication cannot be formed, principally cams and tappets and gears. Modern lubricants are amply supplied with alternatives to cope with the high valve lifts and rapid valve accelerations of high performance engines. Adding moly, or anything else, is totally unnecessary.
 
RichardS said:
Please take one step forward everyone who actually thought he meant 1000. :D

Richard
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Ah but, Richard, he is the pedantic one on these forums, quick to correct anyone who dares to deviate from his view of the world, so quite delicious to be able to correct him!
:)
Stu
 
Normalfornorfolk said:
Why would you want to do this?

If it ever worked for your a Goldie, clubman Bonnie or a Norton SS why did the oil manufacturers not know this when apparently untrained non-technical grease-covered youths riding them did? Or imagined they did. Go figure.

Why would "molly" only work on old engines and not on newer ones?That's not rational. Anyway I thought the experts said Morrison's straight 40 (etc) was the thing for oldies simply because it didn't carry any silly snake-oil.
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When you ran old bangers, as I and many of my fellows did we added molyslip to our oils because it coated bearings and according to a Ricardo report of around that vintage, a test engine had run for some hours with NO Oil and when examined had minimal wear. Of course engines tended not to rely on oil cooling back then. My current bike does rely to some extent on the oil as a heat transfer mechanism. Even my DBD32 did not have a very effective oil filter or a magnetic drain plug and by the time I purchased it had developed an embarrassing thirst for oil (embarrassing for a 350 single anyway). Molyslip was routinely added to the lub oil in a Gas turbine-alternator fitted to RN ships of that era (I can't remember now what the rationale was) and portable fire pumps where the possibility of a poor pick up in the oil tank (dry sump engines) would not prevent the fire pump running long enough to fight a fire.

Modern oils have detergents added to suspend wear parties in the oil which are captured by modern effective filters.
 
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