Choosing the correct Oil for a wet-clutch Motorcycle

I'm a very new rider and just getting motorcycle license. I bought my XJ750 a year ago because I always loved the bike and finally found one at the right time and right price. I've been going through the bike and cleaning, fixing as I go. After reading through the thread and the linked PDFs I decided hogfiddles has it right. I changed oil and filter using Yamalube 10w-40. Thanks k-moe and everyone else for expanding my knowledge of oils and the specific challenges of lubricating and cooling air cooled bikes. Cheers!

 

Hey Spear,
Welcome to the camp.
Strongly recommend you sign up for an MSF course...

 

Thanks Stumplifter, my course starts next Friday

 

Thank you, everyone, for your valuable contributions to this page and site. The importance of good oil should not be taken lightly. I've always been a believer of buying a quality oil regardless of the application. A close motorcycle friend recommended that I use the Lucas oil brand (10w-40 - for my XJ750) and I've been running it since I got the bike a few years ago. After looking up the specifications I found that Lucas meets all the requirements for my XJ750, which is comforting to know that I haven't been mistreating the engine. All that said, I'm a little more curious to try the 20w-50 as temperatures in Saskatchewan (summer) can be in the 70-90+ (20-35 Celsius).

 

That sounds pleasantly cool. 70ºF was the low here last night.
I'd not bother with the 20W-50 unless she's burning oil. 10W-30 and 10W-40 are both suited for air temperatures over 100ºF.

 

I am using the Lucas 10w40 as well. Seems to stand up to the heat of my air cooled Rebel so far.

 

It's easy to choose the expensive oil when you only need 1.5 litres.

 

a note about multiweight oils:

As I understand things, all else being equal, you want the ratio between oil weights to be as small as possible. For instance, measured as a multiplier, a 20W-50 oil's high-weight rating is 2.5 that of the winter-weight, which is a better ratio than that of a 10W-30 oil's 3.0 multiplier. The reason for it is that the oils are kept "stable" (not separating, et cetera) by the addition of long-chain additive compounds. Those additives are less good for lubricating purposes than the oil itself (of course, because they're not lubricants per se), and they break down over time so that the benefits you get for the oil mix degrade, which means you should ideally replace the oil more often. For those who religiously replace oil over a relatively short cycle, that latter concern should not matter.

This must be weighed (pun intended) against the benefits of a multi-weight oil, though. If you find that your bike performs better with a 15W-50 oil, and get clutch slippage or have other problems with 20W-40, you should probably just get the best 15W-50 you can get and change oil frequently (keeping in mind the needs of your specific engine, of course). I get 15W-40 for my XJ year-round, which is a slightly worse ratio than 20W-50, and much worse than 20W-40, though given my climate the 20W-40 (also the manufacturer's recommended oil weight) would be much better during the warmer half of the year, because about the only way I could get a quality 20W-40 here is by paying twenty or thirty bucks a quart to have it shipped from Japan or something like that. Luckily, I can get high quality 15W-40 oils designed for the demanding needs of commercial diesel common carrier shipping.

I won't swear that I didn't give a mistaken account of some specific technical detail or two for why you might want to take note of the ratio in a multiweight oil, but that's what I recall from some in-depth research a while back.

a note about synthetic oils:

Oils are produced from specific base stock groups. In general, if you have the option, stay away from oils produced from Group I and Group II base stocks. These are the inarguably non-synthetic oils. Group III oils are mostly mineral oil based and other highly processed non-synthetics, though Castrol won a court case a while back that lets various brands market them as "synthetic", so what it says on the bottle about being synthetic or non-synthetic is not always representative of the oil's actual nature. Group IV and Group V are inarguably synthetic oils, though, where they start with something that is absolutely not synthetic, purify some components of it, and subject them to chemical synthesis processes to produce lubricating oil, like wine from water.

Oils produced from Group IV and V base stocks are more expensive to produce, so of course most brands go out of their way to avoid giving hints of the base stocks they use. If your oil's label says PAO, though, you've got an oil from Group IV base stock, at least partially. Some oils based on Group III base stock are very good, and others are not very good, but anything Group IV and Group V is expensive enough to produce that I would be surprised to find such an oil that is not very good, because after all that money spent on synthesis there's no point screwing up the quality of the final product. Rotella T-series oils have historically been very good oils for wet-clutch motorcycles (or any motorcycles, really, as far as I'm aware), as have a couple other highly respected oils produced for the commercial diesel common carrier shipping market, because they aren't designed for cars with catalytic converters, they tend to lack higher-friction additives that mundane automobile oils often contain, and so on.

If something doesn't at least claim to meet JASO MA requirements as discussed above, though, you should probably avoid it unless you know something I don't, no matter what base stock is used (and remember that claiming to meet JASO MA without a certification seal means you're trusting the company to test itself). All this talk of synthetic oils is secondary. Only bother thinking about these things within the constraints of the advice given about oil standards by k-moe and others here, when you start getting obsessive about oil selection. It's also worth keeping mind that, beyond a particular point of quality, the price increases for higher-quality oil can be significant over the life of the vehicle, and the returns in the form of reduced engine wear and maintenance costs keep getting smaller. If you have money to burn, though, there's always a more expensive, better oil out there, somewhere.

a note about brands:

I use Rotella in my XJ, and I use Red Line in my Buell. Rotella has historically been a very well-regarded, high-quality, commercial diesel oil that works well with motorcycles, and uses an extremely low-ash formulation, one of Rotella's primary benefits. Red Line evidently uses some of the best base stock synthetic oil process commonly available in US markets.

The Rotella formulation has changed recently, which it will periodically do when emissions standards for commercial diesel common carrier vehicles change. I have encountered some mixed reviews of the new Rotellas that concern me, but I haven't yet put the oil through its paces sufficiently to judge for myself whether I detect any issues. If you want to know how diesel oils for motorcycles perform, though, keep an eye on people who race two-stroke bikes off-road. They obsess over this kind of thing.

In my experience, Red Line has never shown any sign of causing problems and, unlike competing "premium" motorcycle engine oil brands like Royal Purple (and unlike almost every other oil brand in the world), Red Line is (relatively) very open about the formulation of its oil products.

Both of these things are just brands, though. As company executives move in and out, as government regulations change, and so on, brands change, too. If you find what you think is a stellar brand, you should understand that can change tomorrow. You can trust a person, sometimes, but you can't trust a "brand", because the people behind the brand are subject to change.

Let the buyer beware.

a note about advice:

Opinions are like, well, stinky things. Everyone has them, and they all stink. In the end, choose your own priorities; learn what you are willing to put in the time to learn; and make decisions as rationally and dispassionately as you can about how best to meet those priorities. If your plan is to just ride a bike into the damned ground and junk it, because that's what makes you happy, do it (but remember you might want to choose a bike for that purpose that isn't highly valued by someone with different priorities). In that case, oil choice is far less important, and depending on the condition of the bike and the effects on the ride quality you might just get the cheapest bargain-basement oil you used to put in your Yugo. If you care about the vehicle, though, learning how these things work and thinking (clearly) for yourself are the best things you can do to help make the best decisions. Verify every piece of advice you get, when the quality of the advice is important to you.

I'm just some random text on the Internet, as far as you know.

 

That's some solid sounding information, @apotheon . Any sources you can provide? Credentials? Seems to me that you go beyond the average consumer!

 

I'll try to find one of the places I looked up such information. I can think of only one resource that's likely to be findable this long after I looked it all up, but it's a pretty good resource, I think.

As for credentials, I'm just a technically-minded pseudo-perfectionist who often overthinks things and sometimes obsessively researches stuff.

A little more info off the top of my head while I look for info sources:

If you see PAG on your label, or a reference to "polyol ester", those are both Group V base stocks, and polyol ester is the sole base stock used in production of the Red Line oil I use, making it a Group V based engine oil. A great place to find terms to use to search for information about what makes a good motorcycle oil is actually the label of Red Line 20W-50 motorcycle engine oil. If you want to know more, start searching for information about any term on the label that you don't recognize or whose importance in providing a high quality oil is not obvious to you.

 

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.

 

Search for it on https://bobistheoilguy.com/, or the JASO link provided in the first post.

 

Upon further consideration, I think I will continue using Rotella in the XJs. The Kirkland is fine for the cars, but I don't feel like taking chances with the XJs.

Except.... I might try Rotella T6 Synthetic. You know, for science.

 

I'm a big fan of the Rotella oils. I use the 15w-40 T4 in the older bikes with short change intervals, and the 5w-40 T6 in the newer bikes with longer change intervals.

 

Easy, what ever the book says it should be.....simple.

 

without the jaso rating on the jug it may not be suitable for wet clutches. it is not worth the risk of your clutches slipping
diesel oil main thing is it can not be used in motors with catilic converters or it will ruin them

 

Is this the right stuff?
It says heavy duty diesel

 

Yes, @Melnic , that's the stuff!!

 

Yep, that's it. Notice on the back it says JASO MA/MA2.