"Best" oil to use in RFS. (520)

HELP!!! My dealer told me NEVER use Synthetic oil in my bike. He says NONE of those high dollar oils work good with Wet Clutchs, that plain old Castrol GTX 20/50 is the best stuff to run!!! Then, I notice in the manual, it says to run synthetic !!

Mobil 1 motorcycle synthetic...kinda speny but good stuff.


Pretend it's flat and give it the gas.

Mobil 1 motorcycle synthetic is 10W-40, not the recommended viscosity.

There are very few synthetic choices in correct viscosity range, 15W-40 or 15W-50.

Friend of mine with 400EXC likes Motul. Says it makes his tranny shift smoother.

I like Silkolene Pro-4 15W-50 synthetic. My tranny also shifts good, but I note less oil foaming in the sight glass compared to other oils. Seems to release entrained gases. It pours differently too...something about it I like. Also like the red color! One thing I don't like, the price...$10/qt., but I sleep better.


'01 KTM 520 EXC

'95 Suzuki DR350 Dirt

'01 Silverado 2500HD 4x4 Duramax/ZF-6spd

I use Motul as well. I don't spend much time worrying about which oil I use, but I know that as soon as I put Motul in I had no trouble finding neutral - but before I put it in it was tough to find - running or not.


Mobil 1 15w-40 for me. Buy it anywhere - usually for $4.00 per quart or so. 600 miles so far - clutch seems to work smoothly for me. As often as people change the oil in these bikes (me included) - I think just about any oil will be fine for long engine life.

My feeling is USAGE has the biggest impact on a clutch as opposed to which oil is being used. I hardly touch mine except to get moving - so I am not worried about any oil that I used. What hurts a clutch is the amount of heat you put into it - light slipping in 1st or 2nd with little power applied should never be a problem - heavy throttle slipping in higher gears can smoke any clutch with any oil. I think I read a post of someone riding in 3rd the whole time and using the clutch to make an "automatic" out of it. This clutch will not last as long as mine. Point is - the clutch is HIGHLY effected by the rider. With that said - if you are really hard on a clutch - some oils may help it to keep from slipping a little bit longer.

Just my $0.02.


'01 KTM 520 EXC

It does matter what oil you use. Watch out for friction modifiers that are prevelent in a lot of oils. They won't work well with a wet clutch. I use Mobil 1 MX4T. Go to their web site and read about their oils. IMO, this is the one to use! Around $7 a bottle at most any automotive store.

Which Motul ? 300V 5W40 ?? Thanks!

Best is what we are all using isn't it. I use SPECTRO 4 petroleum oil. I'm a big clutch user. Not to shift but to control bike in all throttle ranges. You can call me a big slipper.


(AMA, Dist.36, BRC) Lifetime Memberships

Me too Ret!

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