Choosing the correct Oil for a wet-clutch Motorcycle

Well, that was quick. I started searching, then decided I should double-check to make sure I didn't bookmark some of the info I found. I looked in my bookmarks, and voila: I hit the motherlode with these two links.

• http://www.calsci.com/motorcycleinfo/Oils1.html
• https://www.machinerylubrication.com/Read/29113/base-oil-groups

 

What about Royal Purple Max Gear 75w-90? I was surprised to see what it says on the back of the bottle...
"Max Gear is a versatile, synthetic, non-corrosive, extreme-pressure hypoid gear oil. it excels axles containing open, limited-slip, locker, and spool equipped differentials, Max Gear is also outstanding choice for transmissions and other gearbox applications requiring a GL-5 or GL-4 gear oil.
Max Gear is non-corrosive to soft yellow metals (Brass, Bronze, Copper)...
This product is NOT for use in wet-clutch systems...."

 

Assuming that you're not looking for Corvair advice, it's fine to use (though a bit expensive). The final drive is in no way connected to the transmission or clutch.

 

I use it on my RX-8 which has Synchromesh, after Tons more of research on that, it seemed to be the best and after 2 years, feels great still!
I just happened to have some extra!...

 

I used in in my Zuma 125 that I used to own, but then I was pushing the final drive pretty hard the way I had the scooter set up.

 

After reading all the threads to do with what oil to use, I think I will go with Motul 3000 20W-50 4T Four Stroke Mineral oil as iam in England , JASO MA approved to ensure perfect operating conditions for wet or dry clutches.
Any objections ?

 

Specifications and certifications are more important than the brand. Mogul is known to represent their products accurately, so use it.

 

Now using regular Valvoline M/C 10W40 for everyday riding in my '82 Maxim 750. Used to ride a 920 Virago and my mechanic loved putting Mobil Synthetic Regular 20/50 from Walmart in this bike. On a ride some months later I was trying to pass a car on the 4 lane so I opened up the throttle to do so, only to find the motor was doing great in rpm's BUT nothing was being transferred to the rear wheel ......... clutch slipping like crazy ............ lesson learned. DO NOT USE synthetic oil in an '82 bike !!!!

 

I'd venture to suggest that particular synth oil had a low-friction additive package in it, which your clutch didn't like. Same applies to a lot of the latest car oils - steer clear of any that say 'energy conserving' ' fuel saving' and that kind of guff, as they will have low-friction additives in them. Synth oil on its own is innocent of causing clutch slip.

 

I really enjoyed my motorcycle course and learned a lot!

 

Since this note I've come to realized, synthetic oil does not work well with these old bikes because it will cause the starter to spin. So stick with regular oil.

 

ELECTRICAL CURRENT is what causes the starter to spin

 

I THINK he meant the starter(sprag) clutch.

 

That depends wholly on which synthetic oil is being used. In the past 6 or 7 years several synthetics have been introduced that work perfectly well with the XJ engine.
Regardless of the oil type used, the starter clutch can still slip if the rollers are worn or the starter is not spinning fast enough.

 

I tried belray 10w-50 Syn in my 900 and the starter clutch was Not happy after one ride. I drained it and went back to 15w-40 Rotella. Starter happy ever since.

 

I must admit I dont EVER remember having a problem in the 80's/90's.....and back then pretty much everyone and there dog was using either a 10-40W Dino or in my case a 20-50W Dino.....although I DID use 'car oils' with no slippage of the clutch plates...

Lately, I had been using a 10-40 and 15-40 Rotella diesel........but experienced SOME sprag slip, ....

I've gone back to Yamalube, in a 20-50 grade ( I dont really intend either starting or riding her in much colder weather than we are at in NY-LI region, right now)

Seems to be holing onto those 'clutch rollers and springs much tighter...

 

I've been using Castrol dino-motorcycle oil 10W40 now for the past 5 years and the starter whirl has never returned. It's possible synthetic oil now might work, but dino oil seems to be proving itself for my old bike.

 

I've sworn by T6 ever since I found out about it. I do top off with cheaper thicker conventional to save on costs and leaks, but no, T6 will not cause leaks! What it will do is leak slightly worse, if it leaked before.

T6 is Motorcycle certified and will not make your clutch slip. Where you really see the superior protection is when you tear down an engine with T6 in it (had been sitting for months) the top end was still nicely coated. Conventional would be dry by then.

For my money I think T6 is just a superior product. Its gonna keep viscosity longer, and resist acidification. If you end up storing the bike long term, T6 will stay viable.

 

Does anybody know anything about Kirkland Signature Heavy Duty Diesel 15W-40 (from Costco)?

It does *not* have a JASO rating specifically on the label, but all the other ratings and certifications look pretty much the same as Rotella T4.

If I knew it was JASO compliant, but just without an official JASO certification, I would be willing to give it a try.

3 gallons for $40. Better than a sharp stick in the eye.