I recently bought a 2002 Honda 400 ex. It is piped, jetted and may have a bore kit. I was wondering what is the best kind or brand and weight motor oil to use. Doing a oil change this weekend.

 

Synthetic (Full not blend) motorcycle grade designed for wet cluches. Amsoil is a good one or Royal Purple but there is many more.

 

http://forums.atvconnection.com/showthread.php?t=310709

http://forums.atvconnection.com/showthread.php?t=310291

Maxima Extra!

A performance oil will let you milk a little extra torque and horsepower from the engine. In this category I recommend Redline, or Maxima Ultra or 530MX (in very cold weather).

 

http://www.atvriders.com/articles/oilchange400ex.html

 

I always used Shell's Rotella.

 

There are plenty of oil fights on other forums, so I am not trying to start one here, ok.

A word to the wise however! A couple of years ago, "diesel" oils like Rotella still had a descent anti-wear additive package. Then the government stepped in and decided that everyone needed a catalytic converter, so the additive package had to get downgraded (ZDDP contaminates a cat). Even diesel oils have now been downgraded, just like car oils got the downgrade back in 1993.

One's best insurance of getting a descent additive package is to pick an oil that is API SG (ZDDP is very improtant to your integrated transmsiion, and other high pressure areas like your cam, where the oil is likely to get squeezed out!). The best assurance that it will not make your wet clutch slip is to pick an oil that is JASO MA. The only place you will find an oil that meets both these specs, is in a motorcycle specfic oil! There are a hundred different ones out there to choose from....