what is wrong with synthetic, i run spectro 4 in my kfx400 is that ok how about motuol full synthetic

 

I personally don't think there's anything wrong with snythetic. I was just relaying what Yamaha states in the owners manual about the use of synthetic oil. What does your owners manual say about it?

Upon re reading my post I should have stated the owners maual warns against using synthetic oil as it can cause clutch slipage.

 

The synthetic oil topic has been beat to death.

There is nothing wrong with using synthetics in a wet clutch as long as it does not contain friction modifiers like most auto synthetic do. Stick to the motorycycle synthetics that state they are safe for wet clutches and your clutch and motor will thank you later.

 

It seems most people have good luck using Synthetic oil in their quad.................I didn't. I ran Mobil MX4T (a full MOTORCYCLE synthetic) in my 400EX and it made the clutch slip. Went back to using dino and my clutch was fine again. So I'll never use synthetic if I don't have to.

 

just to add to the oil issue i ran a motul full synthetic in my raptor and it totally fried the clutch in little sahara