Oil Question

68 replies to this topic
  • grayracer513

Posted February 26, 2007 - 03:55 PM


Well, it's fundamentally incorrect, but I can't say if he was blowing smoke, or if you don't remember it right.

The one thing about it that is correct is that single weight oils don't usually have this problem. Multi-grades do not "change viscosities". They are made by taking a light base oil and modifying it with Viscosity Index Improvers (VII's) so that they do not thin out with heat as much as they ordinarily would. For instance, a 10 wt oil is modified so that it thins out so little that at 212 degrees F, it is still as thick as a straight 40 wt would be at the same temperature. So, rather than "changing viscosities, the does quite the opposite, and changes very little at all when heated. Straight grade oils rarely have any of these additives in them, and they can't be beat out of commission if they aren't there.

The VII additives are big, bulky molecules, and most of the less expensive ones used in engine oils are physically somewhat fragile. Transmissions tear them apart, and they can no longer function as they should. VII additives tough enough for use in gear lubes do exist, which is where stuff like 75w-90 GL-1 comes from, but these additives cost more, and since they are not usually required in an engine oil, they aren't used. The oil in your bike is not just engine oil, however.

Any contaminants that would change the viscosity (that I can think of) would do so across the board, at both ends of the temperature range, so I would say such things would also affect a straight grade.

  • RD73

Posted February 26, 2007 - 04:09 PM


That means that the oils mentioned started out as *w-40 or *w-50 weight oils, and during the test, the 40's became 30's, and the 50's became 40's. The same thing very often happens with automotive oils, including Shell Rotella.

Thanks for the PDF Gray. I have seen that before, and I agree about the commerical element of it for purposes of a Sticky. However, your above reference to Shell Rotella made me think that it was included in a test. I thought there were some Rotella results I missed.

  • Leelandc

Posted February 26, 2007 - 04:45 PM


How did the Motul do in the test (thing won't load on my compter) In your opinion what do you think is a better oil. Motul(300v) or Mobil 1.

  • grayracer513

Posted February 26, 2007 - 04:50 PM


The Rotella info was from two UOA's that were sent to me by another TT'r. It had fallen from a 40wt to a 30wt in under 100 miles of road use in a big metric V-twin.

As often as it comes up, I would like to see Amsoil have this same battery of tests run on some of the premium automotive oils that are popularly used in place of a specifically formulated MC engine/trans oil. Some of them would probably do quite well, at least for the most part, but the data would be very interesting.

  • King_Air

Posted February 26, 2007 - 06:01 PM


Grey have you seen any test data on Bel-Ray Thumper oil? What is your opinion on that oil? Thanks.

  • grayracer513

Posted February 26, 2007 - 07:34 PM


Not unless "Thumper" is EXS, in which case, it's in the PDF from Amsoil.

  • Leelandc

Posted March 02, 2007 - 06:57 AM


Thanks alot for all the info guys!!

  • Leelandc

Posted March 02, 2007 - 03:39 PM


What is the least expensive fully synthetic oil you can buy?

  • grayracer513

Posted March 02, 2007 - 04:17 PM


What is the least expensive fully synthetic oil you can buy?

This question appears to illustrate a fundamental misunderstanding of what a synthetic oil is.

It's a curious choice of criteria to say that you must have a synthetic, and then say you want the cheapest one available. There are a number of good blended and pure petroleum oils that would work in a YZF available at reasonable prices that would work better than "the least expensive fully synthetic oil you can buy", whatever that may be. I haven't a clue as to what it might be, but I can only imagine what it would be like, given some of the stuff I've seen on the market.

  • buzzgrizz

Posted March 02, 2007 - 05:31 PM


Does anyone use mobil 1 synthetic 4 stroke oil? If so, is it any good?

Yes I use Mobil 1 MX4T 10w-40. So far i am very pleased with it.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • YZ426F Rider

Posted March 02, 2007 - 07:50 PM


Yes I use Mobil 1 MX4T 10w-40. So far i am very pleased with it.

The MX4T is now known as 'Mobil 1 Racing 4T 10W-40' in case anybody is having a hard time finding it.

  • Leelandc

Posted March 04, 2007 - 02:30 PM


In that Amsoil oil study thing, there is to Amsoil oils. MCF and MCV. What is the difference between the 2 and which is better?

  • grayracer513

Posted March 04, 2007 - 04:27 PM


MCF is a 10w-40. MCV is a 20w-50. Otherwise, they are the same. The same is true of the Mobil 1 oils in the test.

  • gearcutter

Posted March 05, 2007 - 12:41 AM


I am new to this whole dirtbike scene, but I am not new to machinery or oil selection or application. I have seen a couple of these oil threads crop up since I have started reading the forums here, and I havent seen anyone mentioning sampling or testing.

Do any of you guys, or have any of you guys ever sent out a sample of your used oil for testing? In commercial applications where fleets of mining equipment or city transit vehicles are concerened the dollar value of changing oil can be in the hundreds of thousands of dollars. In an effort to maximize service life, and minimize costs, at service intervals oil samples are taken and tested. The test results prevent changing the oil out too early and allow the full lifespan of the oil to be utilized.

I understand that where changing out the oil in a bike costs next to nothing, and doest warrant sampling or testing based on cost, it would still provide hard data that could put a lot of these mythologies to rest.

Testing for me is free, and I was planning to send out samples of a few different brands of oil with accurate hour counts on them just for my own interest. I have always done so with my vehicles so I was planning to do it with my new bike anyways.

Since others would probably be interested in the results I will post them as they become available.

Has anyone else done this?

  • grayracer513

Posted March 05, 2007 - 07:18 AM


Several of us have. This, in fact is one of the things that brought home the seriousness of the problem of oils shearing out of grade. Some of them do that in an alarmingly short amount of time, and one of the things you should focus on in reviewing your UOA's is the tested viscosity of the sample at 100 degrees C (212 F).

Since you're not new to oil sampling, you may already know this, but the oil is best sampled after a normal ride. If you start the engine and run it for less time than it takes it to warm up before taking your sample, your fuel numbers in the test will be high and inaccurate.

  • Leelandc

Posted March 05, 2007 - 12:34 PM


That Amsoil MCF, is this it here??

  • starcruiser

Posted March 05, 2007 - 12:37 PM


Mobil 1 (4T) 15W50 - all you'll ever need.

  • starcruiser

Posted March 05, 2007 - 12:56 PM


I know this subject causes a lot of concern to bike owners because of the potential for engine damage - see your local agent and ask their opinion - and also search online, although there is so much misinformation out there. I ride a Honda XR600R - and oldy but a goody and keep it happy with Mobil 1 (4T) 15W50. If you ride a air-cooled (hot running) wet plate clutch, 4 stroke, then this oil is the business and will put the matter to rest. After exhaustive reading and worry I've chosen this oil and you may find that it's just what you've been seeking.

  • 99yz400

Posted March 05, 2007 - 01:05 PM


I found on Castrol's website that they make a 100% 10w40 Syntec oil.
However, it is listed as a cars/vans/trucks/suv oil. How is a motorcycle oil different from a car oil?

Would 10w40 Castrol Syntec could fit for my YZ400f?


  • grayracer513

Posted March 05, 2007 - 01:07 PM


Note that, in the U.S. at least, there is no such oil as "Mobil 1 (4T) 15W50." There is Mobil 1 15W-50, and Mobil 1 Extended Performance 15W-50, but these are not formulated as motorcycle oils, and might not be shear stable enough to retain their viscosity in a shared engine/transmission application.

Mobil 1 Racing 4T 10W-40, and Mobil 1 V-Twin 20W-50 are formulated as motorcycles, and have been proven stable as to viscosity in lab testing. Both of these are excellent oils.

Related Content


Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

First Hare scramble tips by dhend8

Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • Hot  33 replies

YZ450F 03 Sparks driving me crazy by SirAttard

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.