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diesel oil?


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so I just got my first 4-stroke, an '06 YZ450f.  guy who sold it to me said to run Rotella diesel oil, I think he said 15w30, but I only see 15w40...anyone run diesel oil in their bike?  if so, what kind?  I've always had 2 strokes & run Lucas 10w40 motorcycle gear box oil specifically designed for wet clutches....can/should I run that in my 450?  I would prefer to use something cheaper than the boutique oils that cost $15+ per qt...thanks for any advice

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Haha, one of my first posts was in a similar diesel oil thread. I remember everybody saying "the great oil debate" and I saw its true, these questions always come up. So let me now add my backup for the diesel stuff.

One year now running my CRF250 (beginner-novice means I am far more gentle on my engine, take note) on both track and trail for around 40 hours using Rimula R3X 15W40 and not a sign of any issues yet. Happy I made the switch and the transmission actually feels better than before to me.

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There are different schools of thought on it. Many run it with great results. I have no complaints with it in my diesels but on my bikes I run spectro or Fuchs. I just have a paranoia about using an oil that is designed for engines that run at 3-5k rpms vs 8500+. That being said if you change it often enough you can run anything that won't damage the clutch.

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Diesel oil is not different than other motor oils except for the fact that it contains a soot dispersant.  Diesel engines make soot while gas engines do not, soot is abrasive to bearings and diesel oil suspends it so it can be drained out of the crankcase during an oil change.  Diesel oils will meet API ratings for gas engines like SL or SM but also have a API CI-4 rating, CI meaning compression ignition, for soot producing diesel engines.  Diesels also consume more oil so they generally require a lower ash content while reducing ash content may require reducing key anti-wear chemicals.

Edited by 1987CR250R
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What if they're the wrong additives? None of the API grades quoted address either of the principal concerns regarding motorcycles that share engine oil with the clutch and gearbox.  The first is wet clutch compatibility, and the second is shear stability.  Gear boxes beat the crap out of most engine oils because they aren't blended for the job.  Rotella used to fail at that somewhat miserably, dropping one full grade in 2 hours time or less.  It's gotten better, but I still won't use it.  

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From the samples I have sent to blackstone labs out of my personal bike, Rotella T and synthetic Rotella have held up as well as any other "motorcycle specific" oil I have tried. It has held up better than some of the other "motorcycle specific" oils, most of which cost 3-4 times as much. I did not believe in Rotella for motorcycles until I tested it for myself. It has been a few years now, and personally I will never pay for a boutique "motorcycle specific" oil again.

Edited by KJ790
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Diesel oil is not different than other motor oils except for the fact that it contains a soot dispersant. Diesel engines make soot while gas engines do not, soot is abrasive to bearings and diesel oil suspends it so it can be drained out of the crankcase during an oil change. Diesel oils will meet API ratings for gas engines like SL or SM but also have a API CI-4 rating, CI meaning compression ignition, for soot producing diesel engines. Diesels also consume more oil so they generally require a lower ash content while reducing ash content may require reducing key anti-wear chemicals.

Your first statement couldn't be further from the truth. Are you aware of the different groups of oil and the difference in base stocks? I suggest you educate yourself. There is a whole lot more involved besides keeping the proper grade. Diesel oils are engineered for a low RPM engine with a whole lot of oil in the sump. 11 to 13K and one quart is asking a lot from a diesel oil. Edited by Gunner354
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if you change it often enough you can run anything that won't damage the clutch. 

this is what I was worried about with running a diesel oil. 

 

I am going to order the 20w40 recommended in the manual.  I finally found the oil specs in my manual.  It says to run something without friction modifiers that's "SG" rated.  Castrol Actevo makes a 20w40 & Yamalube comes in 20w40 as well.  manual says to run 20w40 for temps 40 degrees & above.  it says for 60 degrees and below to run 10w40 & Lucas & lots of others makes the 10w40.  I rarely ride below 40 degrees so my choice is clear, run the 20w40. 

 

thanks for all the input

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Don't bother with Yamalube, it shears out of spec faster than any oil I have tried. After 2 hours of riding it had sheared down to a 20 weight from a 40. Running a 15w40 will not damage your bike in any way.

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Don't bother with Yamalube, it shears out of spec faster than any oil I have tried. After 2 hours of riding it had sheared down to a 20 weight from a 40. Running a 15w40 will not damage your bike in any way.

 

Which Yamalube, specifically?  I saw UOA's on their premium synthetic that suggested it had improved.

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My dr650 gets the rotela t6 and 60, 000 miles in 2 years no problems. Yes I ride alot. That being said, the yami gets spectro golden. Partly because the guy I bought it from gave me a few ltrs. W/filters and also because it doesn't get the hours the dr does.

Your DR650 operates at a lower RPM and holds more oil.
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Which Yamalube, specifically?  I saw UOA's on their premium synthetic that suggested it had improved.

 

It was what they used to call Yamalube 4R, now called "Performance all purpose". It even has a picture of a YZ250F on the bottle, but it sure didn't hold up in mine. I haven't done a UOA on the synthetic Yamalube. Rotella T is 1/4 the price of synthetic Yamalube and has held up great in every UOA I have sent. I have sent samples from 5 different oils out of my bike to Blackstone, and the Rotella seemed to break down the least of any of the ones I have sent.

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