diffrerent gearbox oil in KTM models

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#1
why does the KTM manual say you have to use 80W gear oil in the EXC models, while the MXC and SX models can use plain old motor oil?

I changed the oil for the first time this weekend and used PJ1 gear oil, but at $6 a liter, I can't see doing this as often as I normally would. I have always used Castrol 20W50 in all my bikes and it has worked fine.

Is the special oil really necessary????
 

MikeS

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#2
I think you will find that 75wt gearbox oil is close to 10W40 and the 80/85wt is equal to 20W50.

Alot of Pro's and Con's about oil. I would try a few brands and find one that you like. As far as price .... well. It is a expensive bike don't skimp on oil. If you change oil alot,like every race or trail ride,then any bargain non energy conserving motor oil or ATF will work.

I would personally say, get a Oil that is MotorCycle specific and/or Wet Clutch Compatible.
 

KDXfile

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#3
I used ATF type F in my KTM and it worked great. Helps with that notchy shifting. Change every 100 mi. max and make sure you only use TYPE F.
 
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#4
every 100 miles!! what kind of rides do you guys go on? 100 miles in a ride (all offroad, mostly 2nd, 3rd gear trails) is pretty normal for me, and there's no way i could get through a weekend riding any less than that.
mw
 

DanS

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#5
The great oil debate

Will it never end? Try a search and you will find so many posts and responses your head will spin. The one thing most people agree on other than disagreeing is to stay away from oils that have EC in the spec listing. I use Mobile 1 15-50wt in all my bikes. Has not let me down in years and is easy to get.
 

TexKDX

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#7
Dittos to DanS and Strick. One oil for my 2 stroke, 4 stroke thumper, and street bike Beemer.
 
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#8
thanks for the oil advice everyone. I will try a bunch of different oils, and see what I like best.

Now, I was just wondering about the rationale behind why a different oil was suggested for the EXC than for the MXC/SX. I know the gear ratios are different, but thats just different sized gears. The clutch should be the same. The only thing I can think of is you use the clutch alot more in the EXC (tight woods and stuff). So maybe KTM felt the 80W gear oil would work better in this application?
 

DanS

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#9
The only thing I can think of is that heavier weight oil is better at higher temps. Maybe they expect the crankcase temp of the EXC's to run hotter than the MXC/SX because of the type of riding normally done on each. I don't see where that would be the case but it's one idea. It could have something to do with the higher gearing. They may feel that faster spininning gears need heavier oil for one reason or another.
 
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#10
Ktm gearbox oil

To make life simpler: Look at the label on silkolene comp gearbox oil as an example. It has two ratings, one in about the 40 range as engine oil and a second in about the 80 range as gearbox oil. A different rating is given to the same oil depending on its use.