synthetic vs conventional oil

I am getting ready to do an oil change on my 2009 yz450f. I have been running motul 10-40 oil. I was wondering if a synthetic would last longer and lubricate better. And what are some good synthetic oils.

Edited by theyzdude

It really depends more on the oil additive package the blender used than on the type of base stock the oil is based on.  If it was a street bike that had the engine oil supply separated from the transmission, a synthetic would likely hold up longer.  But that's not the case here, and the beating that the trans dishes out is the single most significant thing the oil in a YZF has to deal with.  If the oil was blended originally as an engine oil, and not as a combination engine and gear oil, it will loose a critical amount of its viscosity in such a short time that none of the advantages of synthetic base stocks has any time to be a factor. 


What you will find, though, is that most of the truly durable motorcycle oils with the upgraded gear oil additives are synthetics, or at least petro/syn blends.  My favorites are Mobil 1 Racing 4T (or V-Twin) and Amsoil MCF Synthetic Motorcycle Oil (or MCV).  Motul also makes a good product.

So your saying that basically synthetic oil made for combined tranny and engine will last longer and lubricate better than conventional.

Not exactly.  A conventional oil that is actually formulated for use in combined engine/transmission assemblies will outlast a top tier synthetic that isn't. 


The problem currently is that there is no single spec or standard to conform to that can be placed on the label to make the presence of the higher grade, more expensive viscosity improvers known.  The only oil I'm aware of that provides a positive indication on the label is the above mentioned Amsoil MCF/MCV, which shows compliance with API GL1.   Otherwise, you have to go by published lab tests, or the used oil analyses of yourself or others to know.

So say I buy the amsoil motorcycle oil. Would that be a better oil than the conventional motul oil I have previously been running?

Edited by theyzdude

Probably.  I don't have any test info on the particular oil you're using, but Amsoil MCF is one of the best you can buy. 

Thanks for your help.

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