Molyslip

My concern in twins is that it might centrifuge out and end up in the sludge trap. Any oil guru I have spoken to reckons not to bother. Don't put it in the primary chaincase!

There is some evidence that it is useful in gearboxes.

If you loose the gear oil, either slowly or catastrophically, the Mo disulphide will give protection against seizure for a period of time. It can improve gear changing, although the evidence for that is somewhat subjective.

As stated above, it is not worth putting it in your engine oil, especially if you use a modern high quality lubricant.

In the singles,I have dismantled big endassemblies and foundseveral rollerswith flats worn on them. They have been skidding around the pin instead of rolling. The exact reason I don't know, other than I have read warnings in American big twin magazines to not use any oil additive whichreduce friction in engines due to skidding rollers. Though I personally think this wouldn't apply to twins with slipper shell bearingsso Iuse PTFE additives in these engines and all mygearboxes.Two separate designated products, one for engines and the other g/boxes.

Paul, because the crankpin and conrod eye have different diameters, skidding' of the rollers is a limiting factor even in a caged assembly. At a given engine speed the surface speed of these two components is not identical and the rollers cannot 'roll' on both surfaces simultaneously.So a certain amount of 'skidding' is present by virtue of the design. The rollers defend upon lubricant traction to roll and upon the additives to protect against the sliding which occurs by virtue of this skidding. A good modern 15W40,15W50 or 20W50 oil will give this protection.

In my working life I did evaluate commercial PTFE additives for one of our customers. I saw no evidence of improvement in friction or wear due to them.

A well known US marketer of such products did run into legal problems over claims made for their products which were not substantiated.