Oil

[ACHI]

Is a 20-50w to thick to run is a stock 2004 400 ex?

[sam the brave]

thats what i ran in my 400ex and thw motor is blown so i would say dont use it

[froride1]

There is nothing wrong with running 20/50 in your quad, I have been running it in my 400ex and multiple XR's with no problems. If you live in a cold climate you might want to run something thinner. I live in California and it never gets cold enough for 20/50 to be a problem. If its cold you need to let the engine warm up before you ride but thats it.

[ACHI]

Ok thanks for the reply. I live in So Cal so temp shouldnt be a prob. I always let it heat up for a while before i ride anyway.

[TC426EX]

I use 20w50 all the time. Especially for an air cooled bike like the EX it wont break down as fast as the thin stuff... I would use 20w50 full time in your bike for california climate especially...