Motorcycle Oil


Old 07-08-05, 12:29 PM
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Motorcycle Oil

What is the difference between 10W30 and 10W40 motorcycle oil? Also is there a real difference between automotive and motorcycle oil. The bike in question is a 2004 Yamaha Royal Star.
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Old 07-08-05, 01:25 PM
Join Date: Mar 2005
Location: backwoods of pennsylvania
Posts: 135
10w30 is a lighter weight oil than 10w40. You should be running 10w30 in the winter. Both of the oils you said are a winter oild but the 30 is a less weighty oil. Atleast that is the way it is with car oils. i dont know of a difference between car and motor cycle oil.
Old 07-08-05, 02:10 PM
mancoowner's Avatar
Join Date: Dec 2003
Location: Victoria, Texas, USA
Posts: 138
there is no difference between motorcycle oil and "car" oil.
Old 07-10-05, 02:24 PM
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If your bike has a wet clutch, there is a big difference. Most 10-40, if you look at it close, will say "energy conserving" in the ring on the bottle. This means it has friction reducers added. With a wet clutch you could have a slipping clutch. My 2003 Honda manual says use motorcycle oil or regular oil which does not say "energy conserving" . I would suggest that you locate a forum dedicated to Yamaha's and see what they say. I have learned a lot about my bike at
Old 07-12-05, 11:02 AM
Join Date: Apr 2005
Posts: 28
Depending on the brand there may or may not be a difference between the motorcycle and car oil. I was talking to a Royal Purple factory rep who told me their motorcycle oil is nothing more than their automotive oil with a different label.

In all motorcycles I have ever owned I have never once purchased a motorcycle specific oil and never had a problem with slipping clutch. Currently I run mobile1 in my motorcycle, 10W40. Just got back from a week long 2000 mile trip with no clutch issues.

Use whatever oil you want, in the off chance the clutch slips you can just change oil again.
Old 07-13-05, 08:33 PM
Join Date: Dec 2004
Location: So. Calif.
Posts: 540
your being fed a lot of misinformation , motorcycle oil has a lot more addatives to guard against, heat, higher reving engines, and sheer factor, your bike shares the same oil as the engine, and need the added protection you get from thease other , extra addatives , synthetic is one step above as it is a proven fact that synthetics do not break down in higher temps, your bike is water cooled so this may not be as big a problem as air cooled engines, but the saying stands, oil, even synthetic is cheap , compared to a $ 5000.00 engine and if it were to lock up when it goes it can possibly cause you to crash , not something i would want to gamble on.

lol steve
Old 07-15-05, 12:31 PM
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Join Date: Feb 2005
Location: SF, CA
Posts: 32
Here's my $.02....

The difference between motorcycle oils and automotive oils aren't quite as profound as some make them seem. Zinc and Phosphorous, which are higher in your MC and Heavy Duty oils (diesel), are designed to limit metal to metal wear which shouldn't happen in your engine unless you some how lose all your oil while riding. It is true that SL rated auto oils have a lower amount of these anti-wear additives than with the previous SJ oils.

As mentioned, oils to stay away from are the ones labelled "energy conserving" on the circular API label. Even my manual says that so that is probably a pretty good indication of what not to use.

For the record I run Red Line full synthetic in all my bikes. I don't check the valves on my street bike very often (it's a Honda, LOL), but I look at my dirt bike (Suzuki) valves every few months. I have never seen any wear in either top end though......ever. $10 a quart is a small price to pay for piece of mind. If you want to see what Mobil1 car oil did to my buddy's gearbox, let me know. It ain't pretty.

Last edited by gcvt; 07-16-05 at 01:59 AM.
Old 07-15-05, 08:59 PM
Join Date: Dec 2004
Location: So. Calif.
Posts: 540
orinigal post by Elso , 12/04


I am seeing a lot of debates about oils. If you look at your synthetic motorcycle oils you will see that they are a synthetic blend The biggest issue with using synthetic oils is the affect it will have on a "wet clutch". Although I know several riders who use MobileOne, I would discourage this as with other synthetic car oils. You always want to use the proper weight because the space the oil flows around shafts and other close tolerances is calculated in the tolerance specs by the manufacturer. As far as using an automotive oils in a motorcycle, you need to realize that the oil is subject to much higher heat and has to do a lot more in a motorcycle transmission then in a car engine. Although you can use an automotive oil in a motorcycle it will shear the oil additives much faster and offer far less protection in the long run.

Here is a little research and facts about oil: (I wrote this about 10 years ago so some issues may have changes since then)

One of the most frequent questions I'm asked is "what's
so different about oils and what should I use?" When people have
a question they seem to get as many opinions as they can, which
in the case of oil, only adds to confusion, because there are so
many opinions. Well, I want to give you some of the facts about oil.

One statement I hear quite often is "oil is oil is oil,
it all comes from the same place and is packaged by somebody else".
For the most part this statement is absolutely correct, since a lot
of the finest brands of oil started out as Pennsylvania crude oil,
(Pennsylvania crude being one of the best). What makes one crude
oil better than another, you ask? The better crude thins the least
as it's temperature rises, but that's not real important right now.
What is important is, "motorcycle oil vs automobile oil". The
differences are the additives that are used, both in quantity
and quality. The oil you put in you car is perhaps 10 to 20%
additives. Yet a specially blended motorcycle oil can be 50%
additives. One of the more apparent (cushions things like
transmission gears) additives found in both types are polymers,
(multi-viscosity additives). We all know that oil has a tendency
to thin out as it gets hot, this is where these polymers come into
play. Probably best described as thin (microscopic) strands of
plastic. Have you ever heated a piece of plastic and watched the
results, well if not, the plastic curls. And that is kind of what
happens to these polymers, they expand and curl causing the oil to
actually thicken as it warms up to counteract the thinning of the
crude base.

Now polystyrene-type polymers found in most automobile
oils don't have a lot of strength and will be 50% sheared, or worn
out, after only 2000 miles in a car engine. So you can imagine what
kind of shape they would be in if they where exposed to hundreds or
thousands of pounds pressure between transmission gear teeth. With
that, the polymers in motorcycle oil must be shear resistant and
can cost 10 times more than those used in automotive oils. This
brings me to another very important additive, extreme-pressure

Theory of lubrication is to maintain a film of lubricant
between two surfaces thus preventing metal-to-metal contact and
metallic friction. Though the polymers help in this area polymers
alone can't survive all of the squeezing and shock loads of a
transmission and camshaft lobes. So that's where the additive
"ZDDP" or "Zinc Dialkyl Dithiophosphate" comes in to play,
(Can you say Zinc Dialkyl Dithiophosphate?) Don't feel bad,
I had a tough time with this one. I don't even pretend to be a
chemist. But I do know that zinc, being a mineral, clings to the
metal surfaces so when all else fails the zinc will protect the
surfaces from direct metal-to-metal contact. Now the phosphorous,
an essential element in ZDDP, is limited by law in oils marketed
for automobiles because the catalyst won't survive when confronted
with the phosphorous. But since motorcycles don't have catalytic
converters larger quantities of ZDDP are added to quality
motorcycle oils.

Are you confused yet? These are the two biggest
differences and most costly to distinguish motorcycle oils from
automobile oils. It's safe to say that all motorcycle oils are
somewhat of a synthetic blend. Obviously some more than others
depending on other additives.

If your totally baffled by all of this, don't worry
about it. A good rule of thumb is use motorcycle oil for
motorcycles, automotive oil for automobiles and aircraft oil for
aircraft. Simple as that.

Old 10-25-05, 10:47 AM
Stevetra's Avatar
Join Date: Sep 2004
Location: Asheboro, NC
Posts: 348
Long post my brother, but not good info...
If you were compairing motorcycle oils to oils manufactured in the 70's, you might have a point.
With the oils avalible today, the point is mute.
The only difference between the oils today is the lower content of Zinc Dialkyl Dithiophosphate, and if you select a SG rated "Heavy Duty" oil, like the ones for use in big trucks, there is no difference other than price.
In fact, many oils that are sworn by for motorcycles, are junk.
Studies run in 1994 show the following:

Relative Viscosity Retention
(as a percentage of initial viscosity retained
after normal use in the same motorcycle)

.........................0 miles......800mi.......1500mi
Mobil 1................100%.......86.6%.......83.0%
Castrol Syntec......100%......78.1%........74.5%
Castrol GTX..........100%......72.2%........68.0%
Honda HP4...........100%.......69.2%.......65.6%
Spectro 4............100%.......68.0%.......63.9%

There are 2 major things that alow oils to damage your engine, dirt, and loss of viscosity thru thermal breakdown.

The additives in oils are measured in parts per part per billion is going to cusion a gear or make you clutch slip.

This reminds me of the 5 monkey rule....its a long story..but has to do with 5 monkies in a cage, and a trap door at the top.
Every day they would lower a banana into the cage, and when the monkies went for the banana they would all get sprayed with a hose...till eventually they stopped going for the banana.
Then the hose was disconnected
Then they removed a monkey, and replaced it with a new monkey...when the door opened and the banana dropped in, the new monkey went for the banana, and the 4 others jumped on him so they wouldent get sprayed with water. even tho there was no hose.
The test continued until all of the original monkies had been replaced, and their reaction to the banana was the same, even tho none of them had ever been sprayed with water.

Valvoline, Castrol, and others have started selling motocycle oil, and it is avalible at wal-mart...the price is 1/2 of what you pay at the cycle shop, and they are approved for use in all motorcycles.
They are in fact, re-packaged SG Rated heavy duity truck oil

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