I would still recommend at least a 10W if you do plan on riding in temps in the 40's. The reason I prefer the 5W stuff in those temp ranges is due to the air cooled nature of the motor. They struggle to get up to and maintain temp while in motion, so the thinner oil is just some added insurance in that scenario.

As far as the T6 15w40. I agree with you, it is a damn good oil, even without the price being a factor. I have tested out a few different oils on my Hawks, and the 15w40 T6 has been the best oil I have run, hands down, to date on this bike. This is over Motul 7100 and other popular 4T motorcycle oils. My VFR on the other hand, really really loves Motul 7100.

When you read up on synthetics, and maybe you should if you have any doubts about them, you will see that not all synthetics are equal. The best being Ester base stocks like Motul. The price will cool you off but it is not like you are putting 5 quarts in like a car. Even the price of Motul is cheap given how much you use in a motorcycle and if I had an expensive complicated motor that is where I would be. Oil can be obsessive. I mean when I found out about Ester base stocks I began to run Maxima 2 cycle oil in my weed wacker. OCD not me.

That's no joke. I keep imagining what this or that motor oil will do to my engines when I read the specs :)
Will there be any power gains? Will gears shifts be smoother? Will cold starts be easier? Will it last as long as Brand X? So many questions :D


...I guess that's why oil threads are so popular, huh?

Yet, at the end of the day the most important part of oil has nothing to do with the brand.

The best oil is clean oil. Nothing beats regular maintenance.

+1 on any oil with no friction modifier. With name brand diesel you can't go wrong, a safe bet. Rotella T4 is what I use on anything that doesn't say Honda on it. Then it's GN4 - Sometimes I just want to feel good paying for something expensive and model specific even though it probably doesn't make a difference in the end. But it feels good being a brand whore once in a while.

And SuperTech diesel oil is fine, it really is. Probably Shell makes it anyway lol.

Do you guys feel that a 1k OCI using Rotella 4T 15w40 is too long, ie.. the oil will be too degraded to perform that long? Note: stock/ no oil cooler

tknj99.... I think it depends on the kind of riding. I would have no problem using a 1k interval, given a mix of traffic, highway and off road or trail usage. If you can keep a sort of mental counter, not too specific, but a general "I think I rode a lot going real slow this month", or "most was hignway" or about a 50:50, etc. If you feel you did a lot of riding where the engine was not getting cooled by air moving over the fins, cut it short. If OTOH, you did a lot where there was a good breeze, keeping temps within a reasonable range, ride some more.
I used(still do) pull the dipstick, and take a whiff of how the lube smells. Maybe I'm nuts, but think I can smell oil that has had enough and is ready to be drained & refilled. If it still smells 'good', like it did coming out of the jug, it is likely still good. If it smells 'sour', then it is likely time.
If you stick to a 1k interval, come snow or sandstorm, these engines will be fine. It is not that exacting a design, and doesn't really care. The crankshaft runs in ball bearings, the cam on a bushing that gets drooled on from the rocker arm area, and the cam/crank gears are also gravity lubed. Rocker arms and pushrods have a feed via the rocker arm cover, with drilled passages to drool lube onto the 'right' spots.
As long as there's lube, it should be happy, and doing changes early or late are not critical for longevity. To repeat, it was designed to be poorly maintained, with lubes that are on the level of what you would by at a dollar store, with a 'funny name'.
It does feel generous to baby them, though.
tom

We sell Sunoco Motorcycle oil by the case for those interested. This is not cheap oil. JASO MA/MA2 API SN. The full sythentic is even good in supercharged/boosted engines as well. I suggest people to get a case when they order a bike if they own other motorcycles.

Brozz250.com oil link

PRO Full sythentic 15W-50 and 10W-40
Pro Spec Sheet


GOLD Semi Sythnetic 20W-50 and 10W-40
Gold Spec Sheet

Well, today I bit the bullet and performed my Zong's 700 km regular oil + filter change using a "mixed fleet" turbo diesel 15W40 oil (some generic German "Federal" brand, sorry, no fancy Shell Rotella or Chevron Delvac here), in place of the previous 10W40 semi-synth I used for winterizing it,

Can't go wrong with API CF/CF-4/SJ as well as MB (Mercedes Benz, not JASO ;-) MTU, MACK, VOLVO, CUMMINS etc. OEM approvals, eh?

Well, TBQH there wasn't any difference during starting up (with a semi-warm engine at least) or even a spirited test ride between anything I've used so far. The feeling is in fact very similar (for now) to the 10W40 oil that was in there before, other than the usual "new oil" perks like smoother gear changes, more progressive clutch action etc. Again, for now.


TBQH I expected at least gear changes to be noisier/grindier right off the bat, due to less engineered-in shear resistance, but I guess that's something that only a longer term test will show. If anything, I expect it to lose its properties way before even the 500-600 km a typical moto 4T mineral oil manages.

You might be waiting a while. Most "diesel" oil has a high shear and compression resistance engineered into it, especially under higher thermal loads. It's those properties along with their high detergency to suspend material particles (this sounding familiar to moto oil?) that are the basic hallmark of any good "diesel" oil.

Just for the record, Rotella tests their own oil which "meets the performance requirements of" JASO specs, but is not actually JASO certified.

They administer the test per JASO requirements. No different from any other oil manufacturer out there. It's not like Shell is out there doing some rouge like shady crap.

As a fun side.note, ever notice that T5 doesn't have JASO certification listed on the bottle but t4 and t6 do?

Noone said they were. None of the Rotella oils, which I have been using for over 20 years in every bike I have ever owned, have actual JASO certification. Just being technical, as an oil tech thread should be. Facts are facts.

Why is the T4 better than the full synthetic T6 stuff for our bikes?

(I think it was T6 that’s full synthetic)

Well, for whoever might be interested, here's the one I used:


https://www.intertrade.gr/sonax/Dies...15w-40-4l.html