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So I went to the Hitching Post today (The dealership where I bought my bike) to get some oil anda filter for my first 600 mile oil change. The manual says to use 20W 40. The parts guy says that yamaha doesn't make yamalube in 20W 40 anymore. He recommended 10W 40. I bought five quarts of it, but I havent put it in yet. I am a mechanic by trade, but I am a professional, and I'm required to put whatever oil a specific machine requires which is recommended by the manufacturer. I don't know a whole lot about different weights of oil, and I don't want to start a huge debate about it, but if somebody out there does know a lot about oil, I'd like to know if the 10W 40 is ok to put in this bike, or should I return it and find what the manual recommends somewhere else? I don't trust parts guys. I've worked as a mechanic at auto dealerships and in fleet operations, and most of them don't know crap about anything. I trust you guys more then that guy.
 

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My stealership said the same thing. I asked for a full synthetic oil at the last oil change and they put in 10w40 silkolene. Something I never heard of but after some research the stuff is supposed to be good stuff. I still question the 10w40 weight but its been about 3500 miles since the change and the bike runsextremely smooth. Plus itds still pretty clear when I check the level.
 

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I had a similar experience, went to get oil and filter for the bike from the dealer, grabbed 5qts of what I thought was 20/50 and when I got home I had 5qts of 10/40. Put it in anyhow, and so far no issue, been about 500 miles. That being said I'll be watching this post to see if I'll be performing another oil change soon
 

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The "W" part of the number relates to the viscosityof the oilwhen the engine is cold, and the 2nd part of the number is when the engine is at operating temperature (212°F). So in this case the 10W-40 oil would would have thepumpability ofa 10 weight oil when the engine is cold, and behave like a 40 weight oil at operating temperature.


A 10 weight oil can be pumped easier than a 20 weight so that would be an advantage when the engine is cold. One thing you may want to consider isthe spread between the two weights. 30 (for the 10W-40) & 20 (for the 20W-40) means that the 10W-40 uses a larger amount ofviscosity index improver (VI's) in itsformulation. VI's are polymers which can modify the viscosity of the base stock oil but do not lubricate the engine themselves. These additives can oxidize over time and formdeposits. This is one reason why you don't find many oilsfor sale today that have large spreads between their upper-lower viscosity ranges (5W-50). Synthetic oilsdon't need as much VI improver compared toconventional oils for the same viscosity range, and therefor have extended drain intervals.


I'm sure this 10W-40 will be fine, just try and useanoil with the correct upper viscosity rating which also has the smallest spread.
 

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Being in Minnesota you should be just fine. In fact with your cooler temps the 10W40 might be a bit better.
 

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overheadcam427 said:
The "W" part of the number relates to the viscosityof the oilwhen the engine is cold, and the 2nd part of the number is when the engine is at operating temperature (212°F). So in this case the 10W-40 oil would would have thepumpability ofa 10 weight oil when the engine is cold, and behave like a 40 weight oil at operating temperature.


A 10 weight oil can be pumped easier than a 20 weight so that would be an advantage when the engine is cold. One thing you may want to consider isthe spread between the two weights. 30 (for the 10W-40) & 20 (for the 20W-40) means that the 10W-40 uses a larger amount ofviscosity index improver (VI's) in itsformulation. VI's are polymers which can modify the viscosity of the base stock oil but do not lubricate the engine themselves. These additives can oxidize over time and formdeposits. This is one reason why you don't find many oilsfor sale today that have large spreads between their upper-lower viscosity ranges (5W-50). Synthetic oilsdon't need as much VI improver compared toconventional oils for the same viscosity range, and therefor have extended drain intervals.


I'm sure this 10W-40 will be fine, just try and useanoil with the correct upper viscosity rating which also has the smallest spread.



Vis are added to raise the viscosity number of a lubricant. The SAE J300 Viscosity Classification is used to establish base viscosity ratings.

The Cold Cranking Simulator test has excellent correlation
with engine cranking data at low temperature. All values
are expressed as centipoises (cP). Oils cannot exceed the
maximum value to qualify as a particular weight grade. For
example, oil classified as 10W cannot exceed 3,500 cP of
viscosity at -20°C

Kinematic viscosity measurements are run at 100°C (212°F).
Oil with a W designation must achieve a minimum viscosity in
cSt. Oil with no W designation has to fall within a minimum
and maximum range; 40-weight oil must have a minimum viscosity
of 12.5 cSt at 100°C (212°F) and must be less than
16.3 cSt.


The greater the amont of VIs in an oil the more shearing down can occur. This is measured using the ASTM D-4683 test. What effectively happens is this: VIs are long chain hydrocarbons and over time physically break and therefore no longer boost the Viscosity of the lubricant. This can be seen when changing oil, it comes out of the drain plug like water, but is slow to pour in when adding new oil.

The worry for the engine when running is the second number of the SAE rating, the 40 in 10w-40, if you will. I have no preference when suppying members when it comes to 10w-40 or 20w-50 for the Warrior, it's really up to you. When starting it's the first number.

Lastly there is more to the extended drain issue than just this, there is TBN, the ability of the oil to reduce acids created during the cumbustion process and from oxidation, detergent depletion from buffering impurities, oxidation stability, etc.




More info here. If this isn't enough click and read away.



Hope this helps.

Ashton
 

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Thanks superbee, More than once I have found your knowledge on the subject to be interesting. I have ran Mobil 1 fully synthetic in my bike since break in but I am seriously thinking of changing. Not because of any flaw in the product, but simply because it is a big oil company and the present time I have no respect for big oil or their mistreatment of the american consumer.
 

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Have you had any clutch slippage using the car oil? The manufacture dosn't recommend car oil because it don't have the right friction modifiers in it for the wet clutch
 

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i use Yamaha 20-50w semi -syn. oil . According to my dealer that's good stuff especially for texas.Also i have a yamaha mag that also recommends 20-50w for all air-cooled V-twin yamaha engines.
 

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When i was a mech for yamaha i called there tech line and and they said not to use syn. oil till you have at least 5000 to 6000 miles on your bike because it wont alow the rings to seat properly, and that will lead to early engine somking. Just thought you guys might want to know what Yamaha say's about it
 

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Scoper50 .... there's lots of masterbation going on here about oils as there always is
with no disrespect to others



Bottom line, Yamaha Motors dropped the 20w-40 Yamalube this yearand now stock 10w-40 Dinoas stated. They have expanded their synthetic line of fluids if you go in that direction. Their new'08' factory bike manuals have not been revised yet to indicate this change



Fact, i've never seen 20w-40 in any flavor anywhere except at a Yamaha Dealer
.... If you Google it you might find one prime oil company that list it as i recall.


Here in Socal i run 20w-50 during thevery hot months and swap out to 10w-40 during the colder months. Somtimes i mix. While living in MI i ran 10w-40 exclusively. Stick with an oil that is recommended for 4-cycle wet-clutch application and change it frequently. I've been using Valvoline 4-cycle motorcycle Dino oil almost exclusively for 40M miles.
 
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