Friction modifiers and all the other stuff about oil

[Jaybird]

OK, I stand corrected on the add pack content concerning the Energy Conserving designation. It is a viscosity thing, yes?
I think my main thought was that simply because the oil is Energy Conserving rated, does not automatically mean it will cause clutch slippage.

I read recently that Rotax did some testing and found that only when the oil was thin, and heavy laden with FM would it start to show detriment to a wet clutch. When the oil retained it's proper viscocity, there was no problems with the wet clutch, even with the FM rich fluid.

The author surmized that since any oil tends to shear fast in a motorcycle, that those who would use an energy conserving oil and let the fluid shear to a thinner than intended state, that clutch slippage could indeed occur. Hence the recommendation of oil mfg's to NOT use their energy conserving oil in a wet clutch motor.

If this is indeed the case, which I highly suspect it's a completely spot-on analysis, then what we need to focus on is the frequency of change-out.

And if we know we need to change out our oil before it gets sheared and chewed up by the bike engine, then using the energy conserving oils may be the way to go, since they more than likely contain more barrier additives than the 10w40's and non-energy conserving rated fluids.

I guarantee there has been alot of smoke and mirrors going on in the oil world for dirtbikes. What conventional wisdom says we should use and not use, seems to be shot full of holes and holding NO water.

[mtk]

The author was incorrect.

Any "shearing" of the oil will result in damage to the viscosity index improver additives, which are long-chain molecules that are used to create multiviscosity oils. This process will have no effect on wet clutches or friction modifiers or the like.

As for the Energy Conserving rating, it IS viscosity dependent in that only certain viscosities can get the rating. You can't get the EC rating on a 15w50 oil. But to get the rating, you have pass a Sequence VIB (6B) test and show a certain fuel economy emprovement with the oil in question, relative to some standard base oils. That's the one and only requirement for getting the EC rating on your oil.

The whole problem with EC oils is that friction modifiers are frequently used to help meet the EC specs, particularly on oils with large viscosity spreads in the SAE ratings (SAE 5W50 for example). Friction modifiers are the problem with wet clutches, period. Or should I say, too much friction modifiers is the problem. Oils with low levels of friction modifiers have been shown, in the field, not to cause problems with wet clutches. The older Mobil 1 line of car oils being a prime example. But oils with high levels of friction modifiers most definitely don't work with a wet clutch.

[Jaybird]

Originally Posted by mtk

But oils with high levels of friction modifiers most definitely don't work with a wet clutch.

How do we account for the Redline oils working so well in wet clutch situations? (+600ppm)

[mtk]

Beats me.

However, I've seen, first-hand, Castrol Syntec make a roadracing motorcycle clutch slip within a handful of laps on the track.

[Jaybird]

Many things to consider when looking for the root cause.
An oil may actually change things just enough to push a pre-existing condition over the threashold.
Too easy to simply blame the oil when we don't know the exact condition of the clutch components before such a test.

Any situation like this that I have witnessed always seemed like the oil was the culprit for certain...as it normally happens just after a change of oil.
But further investigation has always shown to be a spring, plate, or basket issue..that was possibly 'accentuated' by a different oil.

Considering that most Syntec I've seen only had anywhere from 0-80ppm Moly (M1 MX4T has like 90ppm Moly), I hardly think that we can consider it a high moly oil.
For a clutch to slip using such a basic package oil, there has to be another underlying problem.

[mtk]

Sorry for the long, long delay in my response but I've been busy trying to get a business started.

As for the clutch in question, it was a brand-new clutch pack, fresh out of the package. One practice with Syntec and it was useless junk. This was also quite a few years ago (1999 maybe) so I'm not sure if the Syntec formulation has changed.