Synthetic Oil

[UncleRico]

My owners manual says NOT to use synthetic oil

I was just curious if anyone knew what the drawback of synthetic oil would be.

[svtbolt04]

Just longer engine life.. But I have heard if you have used non synthetic for a while (more than a year) then making the switch might not be a good idea.

[TRX450R_Racer]

I use synthetic oil in my engine side. I have been since my 4th oil change. I use Mobil 1 15w50 in the engine side. I use Golden Spectro 80W gear lubricant in the trans side. It is equivelent to 10w40 motor oil in weight. I change my oil every time I ride.

[pelele]

Synthetic oil makes your clutch slip when it gets too hot ... i was using mobil 1 full synthetic.. and i switched to semi synthetic and i feel like if i have a new clutch!!!!!  go semi  !!

[TRX450R_Racer]

Synthetic oil makes your clutch slip when it gets too hot ... i was using mobil 1 full synthetic.. and i switched to semi synthetic and i feel like if i have a new clutch!!!!!  go semi  !!

If it was Mobil 1 car oil that is your problem. Car oil will make the clutch slip in a higher HP engine. I don't know if you know but a 450R isn't like your Raptor or all other 4 stroke quads. The 450R has seperate oil in the engine and transmision. I can use car oil in the engine no problem. I use regular motorcycle gear lubricate like a 2 stroke would use in the transmission.

[johnnygun]

synthetic is the way to go in winter (chicago, il) the flow is the same hot or cold, old or new.
if you run your engine oil for a while between changes, it does not break down as fast and protects better.  i'm thinking of using reg oil in summer since i change it after every ride. reg oil never has a chance to get bad and is certainly cheaper.  synthitic oil is very detergent-cleans well. that is why you should not change to it in an old engine. it may remove the goo keepin' it together.
tell me what you guys think about the summer oil thing.