Q: IS AUTOMOTIVE MOTOR OIL BAD FOR A MOTORCYCLE?
A: Not bad, but probably not the best. Why not? It is designed in
reverse order to a motorcycle oil. The priority hierarchy of
automotive motor oil is: (1) Maximize fuel economy. (2) Reduce
emissions. (3) Offer protection for the moving parts. Today's
automotive motor oils do not have the same degree of extreme
pressure and anti-wear agents that they did just a decade ago.
Q: WHEN WAS AUTOMOTIVE OIL AT ITS BEST?
A: Oil changed ten years ago when automakers were pressured to
clean up the air. Since 1993, the entire automotive industry has
worked to reduce exhaust emissions. Automotive motor oil must adhere
to the performance categories set by the American Petroleum
Institute (API). These are called the API Service Categories. The
API categories have been around for 50 years, but for the first 35,
the categories were upgraded six times to meet the demand for higher
The current American Petroleum Institute (API) designation is SL.
The API SL oils are designed to provide better high temperature
deposit control and lower oil consumption. SL oils are missing
important agents that improve extreme use lubrication. In their
place are friction modifiers that improve fuel economy.
Q: WILL AUTOMOTIVE MOTOR OIL HURT MY BIKE?
A: It could. If you're using an automotive motor oil in your
racing four-stroke, you're not buying the best protection. An API SL
oil is missing vital anti-wear components: the most common being
zinc, phosphorus and sulfur. These agents are harmful to the
catalyst that is used to diminish the level of pollutants in
Q: WILL AUTOMOTIVE OIL HURT MY CLUTCH?
A: Yes. The friction modifiers in motor oil improve fuel economy
by making it easier for the gears, bearings, pistons and rings to
slip, slide and turn inside the engine. Unfortunately, these
friction-minimizing agents also make it easier for the clutch in a
motorcycle to slip. If you are using automotive motor oil in your
bike, apart from CRFs, you are losing hook-up and acceleration, as
well as reducing the life of the clutch.
Q: WHY SHOULD I MEMORIZE THE ACRONYM "JASO"?
A: As soon as it became apparent that the American government was
mandating economy over protection, the Japanese Automotive Standards
Organization (JASO) developed a standard specifically for
performance fourstroke motorcycles. JASO designates two different
four-stroke oil classifications: MA and MB. The MB oil is low
friction and the MA is sans the friction enhancers.
Q: WHY ARE MOTORCYCLE SPECIFIC OILS BETTER?
A: Motorcycle specific oils are pumped up with five times the
anti-wear, anti-scuff and extreme pressure additives of regular
motor oil. As an added plus, motorcycle oil does not include
molybdenum disulfide and other friction modifiers that wreak havoc
on clutch performance.
Maxima, a popular motorcycle oil supplier, starts with an API SG
Service Category base oil, the last formulation that wasn't
regulated as to the amount of zinc-dialkyldithiophosphate (zinc,
phosphorus and sulfur) it could contain. Maxima then boosts
protection through a proprietary mix of performance additives. The
end result is a motorcycle oil that doesn't break down under extreme
heat and is tough enough to cushion meshing gears.
Q: WHICH FOUR-STROKE RACING OIL SHOULD I USE?
A: If the bottle of oil doesn't list that it is an API SG Service
Category or JASO MA spec, it's not good enough for your motocross
bike. Although a bottle of oil might say "motorcycle specific" or
"safe in wet clutches," the best endorsement is the API SG or JASO
MA designation. It's better to be safe than sorry.
There is a caveat that applies to CRF owners, however-which we
will clear up in a few paragraphs.
Alphabet soup: To be on the safe
side, if your oil isn't labeled as an API SG or JASO MA oil,
then don't put it in your YZ-F, KTM, KX-F or RM-Z.
Q: WHAT VISCOSITY SHOULD I USE?
A: The most popular viscosity is 10w40. It's thin enough not to
bog down the crank and offers ultimate protection under an extreme
load. Every owner's manual lists the recommended oils, brands and
Q: HOW IS A CRF LIKE A CAR?
A: The Honda CRF250 and CRF450 oil system separates the
combustion side of the engine from the transmission. The CRF
separates the engine sump to keep the metal shavings from the
transmission from floating around in the same oil that is used to
lubricate the piston, rings, and rod and crank bearings.
The upside of this design is that the CRF can use a slipperier
JASO MB-spec oil in the top-end, while using a JASO MA-spec oil in
Q: WHAT ABOUT THE CRF TRANSMISSION?
A: Do not use automotive motor or gear oil in the CRF
transmission. If the gear oil label doesn't have the word "twostroke
gear oil," "safe to use in wet clutches," or the API SG or JASO MA
designation, don't use it.
Q: IS IT BETTER TO SEPARATE THE ENGINE AND TRANSMISSION OIL?
A: Yes and no. Honda uses separate oil for the CRF's top-end and
transmission. This is not a new idea. BSA did it decades ago.
Yamaha, Kawasaki, KTM and Suzuki use the same oil in the top-end and
tranny. Which is better?
Separate oil: The benefit of separating the oil, like
Honda does, is that the top-end is not contaminated by clutch debris
or broken teeth. Additionally, the heat of the combustion side does
not thin out the transmission and clutch oil. The CRF can use an
MA-series oil in the transmission and slippery MB-series oil in the
The downside is that the oil quantity in each chamber is reduced
(to approximately 650cc), increasing the need for more frequent oil
changes. Any oil loss, no matter how small, becomes critical when
you have a small pool to draw from.
Shared oil: The benefits of using the same oil throughout
the engine, like the RM-Z, KX-F, KTM and YZ-F, are that the large
supply is less likely to reach critical levels, overall engine
temperatures are reduced and oil changes aren't demanded as
frequently. On the downside, shared oil engines must use an
MA-series oil for the clutch (which means that the top-end doesn't
get the benefits of the slippery MB friction modifiers).
CRF twins: Honda CRF250 and CRF450
owners can use a JASO MB oil in their top-ends and a JASO MA
oil in their transmissions. Everybody else must run an MA or
SG oil. Say what?
Q: WET SUMP DRY SUMP OR SEMIDRY SUMP?
A: Don't get tconfused by these terms. By definition they are
different, but in action they all work about the same.
A wet sump engine has a pool of oil in the crankcase. A dry sump
engine doesn't store oil in the crankcase, but instead in a remote
tank and the oil lines. A semi-dry sump engine is, in reality, just
a marketing term for a wet sump engine that tries to elevate the
crankshaft out of the pool of oil.
The Yamaha YZ-F is a dry sump design. All other four-strokes use
wet sumps, although they go to great lengths to avoid the negatives
of an old-school oil pan under the engine. Suzuki and Kawasaki
coined the semi-dry sump terminology, but the KX-F and RM-Z are at
the very least semi-wet sump engines.
Q: CAN OIL MAKE MORE HORSEPOWER
A: Yes. Special blends of low viscosity ester synthetics can
protect like a 30W under extreme use, but let the crank spin like it
has a OW. Zero weight is the same viscosity as water.
But, the real secret to getting horsepower out of four-stroke oil
is to use less of it. Most modern four-stroke engine designers try
to keep the crank (and even the transmission gears) from being
submerged in an oil bath. It takes horsepower to slog these parts
through heavy oil. Thus, lessening the amount of oil that pools at
the bottom of the crankcase or gearbox increases horsepower.
Q: HOW OFTEN SHOULD I CHANGE MY OIL?
A: Yamaha recommends changing the oil and oil filter every five
rides. Honda's Eric Crippa advises changing the engine oil as
frequently as possible and changing the oil filter every fifth time.
One of the problems with a frequent service regimen is that it
provokes people to use cheaper oil.
Q: CAN I LEARN ANYTHING FROM MY OLD OIL?
A: Yes. Pay careful attention to the condition of the spent oil.
If it looks and smells dirty, you need to service it more
frequently. Extend the time between service intervals if the oil
appears and smells clean.
High-end race teams, Formula 1 and Reno Air racers send their
used oil out to have it analyzed. Laboratory tests can use a
spectrograph to determine what metal particles are in the oil-and
whether that particle evidence could be pointing towards a potential
failure. This is too expensive and extreme for a local racer, but
you should always sift used oil for broken clutch plates, teeth from
gears or any 'other unusual conditions.
Q: WHAT OIL SHOULD I USE IN MY FERRARI?
A: Unless you are a factory rider, you can skip this question. If
you want the best protection for your 360 Modena Berlinetta, run an
Ester Synthetic, API SG, JASO MB, four-stroke, motorcycle racing
Small print: You have to look hard to find the service
categories, but don't give up. Under the "SAE 10W40" number, Maxima
lists its Maxum4 oil as exceeding API SG and JASO MA standards.
Eagle eye: If you see the word "Moly"
on a bottle of oil, keep it away from the tranny on your
Small print: You have to look hard to find the service
categories, but don't give up. Under the "SAE 10W40" number,
Maxima lists its Maxum4 oil as exceeding API SG and JASO MA