Is it o.k to run Mobil 1 synthetic 15W50 in my 400ex? Will the clutch slip? I want to use a heavier grade oil than the regular 10W40 from honda. My bike smokes a bit and think better oil will help. If the mobil 1 isn't any good, is formula 1 20W50 any good? Please let me know what you know and think. thanks

 

I don't have experience w/heavier weights, but I have run 10w-40 in my 350x for about 2 years and have had no probs.......yet.If you use it just pay attnetion to your clutch[slippage].

 

If it is smoking with regular oil it will smoke worse with synthetic. Synthetic is much slicker and will get past worn areas more than convential oil. My pickup with 175000 miles on it uses about 3/4 quart every 3000 miles. I tried mobil 1 thinking it would help and it used a quart in 850 miles and smoked at startup much worse.

 

yes, try mobil 1 15w50. several 400ex owners have said that it fixed a smoking problem.

 

Ya I run Mobil 1 15w50 in my 400ex and have been using it for about a year now with no problems and only good results.

 

I use it in my '99, it doesn't smoke anymore and it runs alot cooler. I was a little weary about using it also. I'm convinced now though, that it is okay to use.

 

Yes, the synthetic will be fine...

Don't buy into the wives tales about clutch slipping, leaking, and especially the guy that says it will make your bike smoke worse.. I'd like to hear some technical data to back that up..... Synthetic oil is not "more slick" than conventional oil, it is, however, less prone to premature breakdown, has better cold pumpability, much better resistance to high oil temperatures which is probably it's most important property, is generally more shear stable due to less, if any VI Improver, etc...

Anyways, it should clear up your smoking problem as it did on mine - as long as there isn't any cylinder or ring damage. The EX breaks down conventional oil rather quickly & runs very high oil temps.

I have a 350X as well and never had any trouble with conventional oils in it, but the 400EX develops more HP, is under more of a load, and thus deveolps more heat (plus it's oil cooler doesn't get as good of air flow as a 350X), apparently enough so to break down the oil. Mobil1 15w50 was my cure, I will never run anything less in my EX again.

BTW - I have an 11:1, cammed, ported, FCR carb'd EX that is running on it's original clutch without any problem & my bike gets raced as well.