96 CR250 and 02 XR100 crank case oil ?

[Jackyl]

Alright, I've been running Castrol Syntec full synthetic 10w-40 in my 1006 CR250 for about two years with no problems, so I put the same in my girlfriend's new 2002 XR100. The guys on the XR forum tell me that it will destroy the clutch, which I can understand, but wanted to make sure this was a valid concern, and see it the same holds true for my CR. If so, should I run a regular "dino" motor oil or do I need to always use Honda oil? I switched to synthetic in the CR because I drain it after every ride, and it is always a really deep grey aluminum color and not see through at all. If I do need to switch, will it be alright to do so after running synthetic for so long in the CR? Thanks guys!!!

-AR

 

[MXTex]

If it hasn't hurt your CR clutch; it won't hurt the XR clutch. They're both wet clutches and I don't think 10W40 has friction modifiers. It should be OK to run in both bikes. With that said, it would not be OK to run two stroke specific gearbox oil in the XR's gearbox. This is due to the fact the an XR's crankcase serves the transmission and reciprocating assembly and thus needs motor oil. Shifting from synthetic to fossil oil is not a problem so if you want to go back to dino oil; go for it. Recommendation; run a two stroke specific gearbox oil or ATF type F in your CR. Run fossil based 10W40 in the XR and change often.