Truth about sytec

I have read that it is not advisable to run fully synthetic oil in the 4 stroke motocross bikes because they have a wet cluch and it will cause it to slip.

Since I have come to realize that this forum is full of good and reliable information, I thought I would ask if anyone on has used fully sytec in a thumper or known someone who has because some of these DO NOT's on the internet are just specualtion or wives tales.

The reason I ask is because I have 4 quaters of Repsol fully synthetic 10W-40 that I use for my GSXR-600 but since I am not going to be going back to the track untill the spring due to cold weather, I thought I would try to put it in the dirt bike I just bought. Is this seriously a bad idea?

I use fully sinthetic oil (10w 40 mobil one, just for thumpers) in my two bikes.

It will not affect the wet clutch system.

You must run the same API rating oil/synthetic lubricant as is recommended for that application. There are synthetics and oils that will contain friction modifiers, emulsifiers, anti foaming agents, and a variety of other additives that will cause a clutch to slip. In fact Yamalube 4R is a semi synthetic 10W-50 non friction modified lubricant. Look for a SH or higher non friction modified lubricant only.

i run the full synthetic silkolene pro 15w40 in my 06, no problems as of yet, seems to work fine.

That's an old-school myth. The oils that MAY cause clutch problems are any that are graded API "EC II" (energy conserving II), and most oils that qualify as EC II are, in fact, synthetic. But it is NOT TRUE that most synthetics are EC II.

In fact, many that are marketed as motorcycle oils carry that JASO MA grade, which certifies compatibilty with wet clutches, and very few commercial (API C*) are ever EC II.


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