Just thought I'd share my find.
It's winter, it's really cold, and I'm still riding.
Ran the bike mostly on 10W-40 for it's life, switched to Rotella 15W-40 this past spring. Perfectly happy.
Since it's getting a little cold to turn over 15W, I thought I'd do some reading of the back of the oil containers, looking for the JASO-MA certification in a lighter oil.
Noticed a liter of Rotella 5W-40 synthetic and sure enough it's JASO-MA.
I think I found my winter oil.
I'll report back when I need to start her up on a 0-10ºF morning.

 

I'd bet a nickel that you'll have no problems at all. If my 400+ hp hemi can run 5W-20 in the heat of the summer, I'm sure 5W-40 for the ol' KLX in winter should be fine.

 

That oil is a good choice year round

 

I use the 5w-40 in both of my other bikes for almost 10 years now-great stuff. I would run it in the KLX but for some reason EBC doesn't want you to use synthetic on their clutch plates so it's the regular Rotella.

 

I just look for the JASO-MA, just because. Who really knows if it makes a difference in engine life, but I figure for me at the price of Rotella it isn't worth not running it.

Until someone (don't look for me to do it) actually does the full on test, running comparable engines on oils until they blow up or they do the Consumer's Reports type test doing a tear down and measurement to start and then to finish after a bazillion miles to see what the wear actually is, we'll never actually know. We'll just all do whatever we want... and that's fine with me.

 

I was running the rotella 5-40 t6 when my exhaust cam melted into the head. Certainly can't say it was the oil, but there was oil getting to the head when this happened.

also worth noting, I did not put the big bore kit in myself so I have no idea what really caused it, I'm still a little weary of running 5-40 at least in the warmer weather. Stocked up on some Kawi 10-40, fingers crossed.

 

Taking for granted that the oil was full level, I'd have been real curious about the oil passage to the exhaust cam and other installation/build questions related to the cams and oil starvation. One other possibility, if for some reason the cam chain tensioner was overly tight due to installation error or adjustment. Those are the things that would cause a failure you describe. No oil or a cam drive tightened so tight it would pull the cam tight enough to cause the film of oil to be broken allowing the metal to metal contact causing the seizure. Those are the kind of failures I've seen I've never seen an actual oil break down failure. All have had oil starvation due to either mechanical root cause or extremely low oil level.

One point to your comments on the oil weight - 40 is 40 within the oil industry specs, making the 5w40 perform the same as the 10w40 at full operating temperature. But I do understand the reservation when one has had problems when using some products.

 

Finally broke down and read an oil thread - this one.. I expected more laughs..

 

Oil is not a funny subject... unless you slip in a puddle of it and fall on your butt and your buddy posts a video of it on YouTube! _ _

Maybe we need an oil dry thread! Is cat litter better? Saw dust? oil-dry? pads? left over diapers? Maybe reference a few Brit and HD forum links...

 

That 15W40 Rotella was probably originally formulated for 500+ hp/1600-2000 ft/lbs diesels that are running on lighter oils now. Detroit Deisel recommends 10W30 in their new engines and up to 50,000 mile change intervals, depending on the application. They claim it's just as good for the engine as the 15W40, and fuel mileage will improve up to 4% (1% is more realistic). I sent our oil sales rep from work a list of what engines we are running in trucks from 2008 and up (various Cat and Detroit models), and he got back to me that not only are they all suitable to run 10W30, but they just put a 5W30 on the market that we could use as well. Idk if I'll try that one just yet. Then he asked for a list of the older trucks, because they could probably be switched to something lighter, too. I'd have a hard time changing a million mile truck to a lighter oil.

Too far off topic???

Point is, with the advancements in oils we could be running 0W5 in a few years. Who knows?

Happy new year KLXers!