Stirring up the oil debate again!


Mi. Trail Riders
Dec 6, 1999
Just when I thought the 4 stroke oil debates were subsiding, I read this in the lastest Dirt Bike magazine:
"Thumper Racing reminds four-stroke owners never to run synthetic automotive motor oil (like Mobil 1) in your motorcycle, as the clutch and gearbox bread down the lubricating components that your crank needs to live."

So, now what? :think

I just started running Mobil 1 in my WR400 too! :scream:

Bob Brooks

Jan 6, 2001
I saw the same article, which definitely contradicts a lot of the information I've read on this forum concerning motor oil. Incidentally, I just started using Mobil 1 15w-50 in my wife's XR250. I've never used Mobil 1 before, but based on the advice given here and the availability and price of Mobil 1, I switched. Any retorts from the oil guys here on that remark? Is it just propaganda from the magazine and Thumper Racing, promoting their buddies at Maxima and other motorcycle oil companies?


Feb 12, 2001
dirt bike mag? these are the same guys who use the term "decompression braking" all the time so they think they sound smart. since i was about 7 i think i knew that it's really "compression braking" that describes the drag caused by a decelerating 4stroke engine. every road racer/autocrosser on the planet knows this.

as for the oil, most mobil 1 grades contain friction reducers designed to increase mileage in cars. in fact this could be said about automotive oils in general. it's been said that these friction reducers may cause clutch issues.

however, some oils, and specifically mobil 1 15w50 (the RED cap) *do not* have these friction reducers. in the API circle on the back of the can, there will be no "Energy Conserving" wording. there are a million theories on what brand oil is "best". no one knows, and your application (e.g. trail riding in colder climes) is going to be totally different than the next guys (e.g. mx racing in the hot sun).

so use whatever non-EC oil you want, and change it frequently. if in doubt, read your manual and use exactly what the manufacturer recommends. as for what you hear on DRN-- why the hell would you trust a bunch of people who you never met, can't blame, and for all you know are just AI bots a la The Matrix? :eek:

the wrooster


Mi. Trail Riders
Jan 1, 2001

For what it is worth, I have never put anything but plain old Valvoline (10w-40 or 20w-50) in my XR250R for the last fifteen years. Granted, I change it more often than most XR owners do but, as you know, that engine has never been apart and it is now fifteen years old! What is even more amazing is that the clutch has never slipped and it still does not burn any oil!

Kinda says a lot about the theory that clutches and trannys break down the oil and destroy its lubricating abilities. I think I will continue to experiment with the Mobil 1 synthetic in my YZF. At four dollars a quart I will be more inclined to change it than if I were spending six or eight per quart.


will pattison

Sponsoring Member
Jul 24, 2000
Originally posted by Bob Brooks
snip...Is it just propaganda from the magazine and Thumper Racing, promoting their buddies at Maxima and other motorcycle oil companies?


rich rohrich convinced me. i run mobil 1 15w-50 in my 400, my 426, and my wife's ttr125. no issues, and i can buy 2.5x as much of it for the same money as the motul i was using.


Jul 31, 2000

It's got to be propaganda. I have been running Mobil 15-50 for about 8 months and had no issues so far. I change my oil regularly, but not as often as some other guys. I am no expert, but I think you'll find that a lot of the riders here feel pretty comfy with Mobil....and I like the price tag and availability.
As a matter of fact I use Mobil 15-50 in everything that has a motor. That way I don't get so confused all the time:confused:


Damn Yankees
Nov 21, 2000
I switched to Mobil One 15w50 with the red cap and NO EC rating ( Additional friction modifiers). I have used it since January in all the bikes. No failures.

In my VOR I don't even get the clutch fuzz on the magnetic drain plug any more. The stuff just looks clean as I put it in after 5-6 hours of riding. So I ran two enduro's on the same 1.25 quarts. Drained it today and it was clean. I don't think its hurting my VOR any.

I think that article was a generalization targeting the many synthetic oils for automobile applications with those friction modifiers identified by the "Energy Conservation" rating in the circle on the back of the bottle. Mobil One 15w50 isn't the typical oil suggested for these new cars. Most have the 5w30 or 10w40 rated oil as a recomendation. All those lower weight synthetics have that EC stuff that can cook a clutch. That's why the article made the generalization is my guess because its easier to make a safe generalization that parse out the exceptions such as Mobil One 15w50. ( All the lower rated Mobil One Oils have EC additives). Nothing really synister here....:)


Mi. Trail Riders
Dec 6, 1999
I think somebody's got their head screwed on backwards on this Mobil 1 issue, either at Dirt Bike or Thumper Racing - or like someone said, it's propoganda to sell more Maxima. Think about it - why would clutch and gear action shear oil worse than engine actions? The clutch and gears turn about 10 times slower than the engine itself, generating a lot less heat, and certainly less shearing action that would break down an oil. The action of a piston against a cylinder, or a valve against a guide, or the cam chain on the sprockets certainly would be worse in my mind than gears.

I posted the Dirt Bike thing because I knew it'd get a rise - the "which oil is best" message threads are second only to the "which bike is best" thread in terms of opinions and ideas.

Of course, we all know Yamaha makes the best bike....:p

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