weight of oil for 2005 yz250

[rap225]

the parts man at a dealership where i bought my cycle suggested that I use 80 weight bel ray gear box oil. the manual calls for 10w30. has anyone ever used 80w oil. seems like it would be too thick.but he said it gets real hot in there and it helps.

[KX02]

Originally Posted by rap225

the parts man at a dealership where i bought my cycle suggested that I use 80 weight bel ray gear box oil. the manual calls for 10w30. has anyone ever used 80w oil. seems like it would be too thick.but he said it gets real hot in there and it helps.

Well your parts man is about half right. 80W gear oil is fine to use. I used it in my last bike. Gear oil and motor oil have completely different methods of determing their viscosity. An 80 wt. gear oil is basically about as thick as a 10W-30, so it is not a matter of getting hot and thinning out. I recently switched from 80W gear oil to using type F automatic transmission fluid. It works great and it's cheaper than a specialty oil like Bel Ray or the Castrol MTX I was using.

[Reuel]

Yea, in the gear oil world, 80w=10-30w and 85w=10-40w. If you research some of the oil manufactures they talk about this. Here is a quick link to Spectro gear oil where they mention this. Scroll down to the "GOLDEN SPECTRO MOTORCYCLE GEAR LUBRICANT " and you can see this. One of the oil mfgs has a good write up on this but can't remember which one it was.
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[Kenny400]

Depends on the application too. An 80 or 90w AUTOMOTIVE gear oil (or what we call "rear axle dope" ) is going to be alot thicker than MOTORCYCLE specific 80w gear oil.

[Reuel]

Originally Posted by Kenny400

Depends on the application too. An 80 or 90w AUTOMOTIVE gear oil (or what we call "rear axle dope" ) is going to be alot thicker than MOTORCYCLE specific 80w gear oil.

Yea, good point. The automotive gear oil, the stinky stuff is NOT for your bike.