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Which tran oil am I sposed to use?

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I'm finding a bunch of "oil change kits" for the CRF450X with 85w trans oil, but the service manual says to use the same 10w30 in the tranny that you use in the engine.  What's up with that?

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<< What's up with that?>>

Basically that with the change intervals recommended, you can use the same oil without significant impact to the tranny.

85w trans oil is not really higher in viscosity over motor oil like the number suggests (it's approximately equivalent to a 40w motor oil), but rather it is a different formulation meant to work with the high pressure that occurs between gears.  Many use it though because it helps with shifting and lets the tranny live longer.  But that's not something you want in your engine.  

Normally in a CRF, the engine side and tranny side are considered separate, but it's done with a couple of seals between the two sides.   If one of them starts to leak, then either tranny oil ends up in the engine side, or engine oil ends up on the tranny side.  The first is a problem, where the second is not.

 If you use the same oil in both sides, then it doesn't matter if a seal starts to leak.  

 If your good about checking your oil level before every ride, then your probably safe enough using tranny oil if you want to on the tranny side.

Jim.

 

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you do not want an oil with moly in it on the trans side.your clutch won't be too happy

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Maxima mtl 80w. Never had a single transmission issue or failure with this oil. Just be sure to run a full quart in trans side. 

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you do not want an oil with moly in it on the trans side.your clutch won't be too happy

Can I ask why? I've only been told to run it with Moly. Is there something wrong with running Moly?

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2 hours ago, kgish475 said:


Can I ask why? I've only been told to run it with Moly. Is there something wrong with running Moly?

Moly is short for molybdenum disulfide.It is a friction reducer!Since your trans also lubricates your clutch it will make it slip or not engage lie it should.Moly additive is fine for the engine side!

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Moly is short for molybdenum disulfide.It is a friction reducer!Since your trans also lubricates your clutch it will make it slip or not engage lie it should.Moly additive is fine for the engine side!

Thanks for the clarification. Think I'll stick with the HP4 85W then

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