Rotella 5w/40 or 15w/40

[RCinNC]

I put about 20,000 of the 93,000 miles on my my S10 using Rotella T4 15W-40. It worked fine. However, I stopped using it back in 2020, because though Rotella still carried the JASO MA/MA2 certification for a wet clutch engine, it stopped carrying the API certification for gasoline engines. Those are the SN, SL, SP etc certifications. If you look on the back of the Rotella jug, you'll see that it now only carries the API certifications for diesel engines (those are the certifications beginning with "C"). I suspect they stopped trying to meet the API standard for gasoline engines because of the amount of zinc that's in what's essentially a diesel oriented motor oil. Excess zinc can cause premature failure of a catalytic converter. I don't know how likely this is to occur while using Rotella in a Super Tenere, or what the end result would be from a failed catalytic converter with regard to performance; I suspect that, at the least, there would be an issue with the engine being able to breathe properly, since the exhaust would be restricted while it was passing through a clogged converter. The exhaust pipe assembly (where the cat is located) is a $900 part, so I figured I'd err on the side of caution and stop using the Rotella.

Like I said, I don't know how likely it is that the Rotella would have any effect, but since there were other oils available that did have the gasoline certification, I switched back to them.

 

[RCinNC]

I did a little searching and found that Rotella does now offer a product called Rotella T4 15W-40 NG Plus, that carries the certifications for gasoline, diesel, and natural gas powered vehicles. For gasoline engines it carries the SN certification. What I couldn't find information on was whether it has the JASO MA/MA2 certification. That isn't mentioned on any of the sites I found on line referencing the product, and I haven't seen the rear of an actual container of the oil that shows all the certifications. I've never seen it in a store.

Not having the JASO MA/MA2 certification doesn't mean it isn't safe for a wet clutch; I used O'Reilly Auto 10W-40 for about 24,000 miles, and it doesn't have the certification. Not having the certification either means that the company didn't go to the added expense of having the oil certified, or that it actually does contain friction modifying additives that do make it unsafe for a wet clutch. I believe the ones that have unsafe friction modifiers are sold as "energy conserving" oil, but I don't know if there's a uniform standard there that you can rely on (that's why they developed the MA/MA2 certification).

 

[RogerRZ]

I buy Rotella T 15w40 Dino by the 5 gallon pail, and use that in everything except for my four wheeled road vehicles (And of course, my two-stroke stuff). It's just anecdotal, but it's not done me wrong yet.

 

[Bmwdumptruck]

20+ years ago I was running my only other Yamaha, a 99 YZF600R (Thundercat in uk). My local dealer in town, a pretty well known racer with some interesting custom built racers, told me I shouldn’t use the Mobil1 fully synthetic oil as per yamahas recommendation. He considered it glazed/polished the bores too much leading premature oil consumption. I never found out as I traded the bike by 22k. But I’ve generally only used semi in just about anything I’ve ridden since. But now I’m back on a Yamaha and he’s now saying use the Yamalube; according to his son who now works with him. ?? Is he towing company(yamaha)line?
I’m picking up a couple of parts Sat morning, might try and see if I can catch him.

 

[Little Joe]

Interesting. So you are saying the 15/40 T4 dino oil would be your choice?

It is the best bang for buck and all I have ever used in my FJR since testing. ( the testing got started because I didn’t like the FJR whine and T6 5-40 made it worse).
I would not hesitate to use it , and in fact it is presently in my DR and ST.


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[nd4spdbh]

It is the best bang for buck and all I have ever used in my FJR since testing. ( the testing got started because I didn’t like the FJR whine and T6 5-40 made it worse).
I would not hesitate to use it , and in fact it is presently in my DR and ST.


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I have almost exclusively used T4 15w-40 standard dino or T6 5w-40 in my motorcycles for the last 2 decades and have never had an issue, I mainly switched to the T6 full syn "cus synthetic" many years ago on my 2014 WR450 and have just stuck with that for it and all other bikes. But sounds like the S10 would be better off with the 15w-40 T4 given its transmission setup (and then just change the oil more often than a typical synthetic OCI)!

 

[Fennellg]

Well if by chance my cat become full I will just remove it. They don’t last forever. Sooner or later they get clogged up. Look at the bright side. Your bike will sound good, have more power, and run cooler. No one that I am aware of has trashed their cat by using the Rotella stuff.

I will chew that food when I have to. I have had a 2 cycle outboard Seize up, When a friend decided to try out a fancy synthetic oil. When engines get old I don’t like to change their diet.