Dirt Bike 10W-40 Synthetic Motorcycle Oil

10W-40 Synthetic Dirt Bike Oil Designed to improve the performance of bike and rider. Consistent clutch feel is the result of “friction durability,” so whether deep into a race or deep in the woods, riders can feel confident their clutch will perform from start to finish.

SKU: DB40 Category:

Dirt Bike 10W-40 Synthetic Motorcycle Oil

A top seller!!

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AMSOIL INC., the premier manufacturer of synthetic motorcycle lubricants, focuses on improving lubricant performance so riders can focus on improving their performance on the trail or the track. That’s why AMSOIL is the Official Oil of Monster Energy Supercross, AMSOIL Arenacross, AMSOIL GNCC and the AMA Amateur Nationals.

Delivers Confidence in Clutch Feel

This is what sets it apart from the other 10W-40 Motorcycle Oil and ATV oil lines..

AMSOIL Synthetic Dirt Bike Oil’s superior friction-durability properties help minimize clutch slippage, fade and chatter, giving riders consistent clutch feel during takeoffs or when maneuvering around obstacles on the trail. In an extreme simulated-start test, AMSOIL Synthetic Dirt Bike Oil continued to deliver consistent clutch feel following 32 simulated race starts, while a leading original equipment manufacturer (OEM)-branded oil demonstrated inconsistent clutch-lever action and poor clutch feel after 16 starts. The clutch plates lubricated with AMSOIL Synthetic Dirt Bike Oil remained clean and in good overall condition, while the plates using the OEM oil revealed discoloration and wear. AMSOIL Synthetic Dirt Bike Oil’s superior performance helps instill in riders the confidence that their bikes will perform consistently in all types of riding conditions.

Protects Against Wear

AMSOIL Synthetic Dirt Bike Oil withstands high-rpm operation, extreme heat and mechanical shear. Its synthetic base oils naturally resist viscosity loss and provide a protective film against wear to gears, bearings and pistons. Its anti-wear additives provide an extra measure of protection, promoting long component life to help riders get the most out of their bikes.

  • Delivers confidence in clutch feel
  • Superior protection against gear, bearing & piston wear
  • Maximizes horsepower
  • Helps extend clutch life




AMSOIL Synthetic Dirt Bike Oil underwent extensive on-track testing in the bikes of professional riders. A combination of racer feedback and lab testing allowed AMSOIL to fine-tune AMSOIL Synthetic Dirt Bike Oil for outstanding wear protection and consistent clutch feel ‐ benefits riders demand.

APPLICATIONS for the 10W-40 Dirt Bike Oil

Use 10W-40 Synthetic Dirt Bike Oil in dirt bikes that require 10W-40 motorcycle oil, including those made by Honda*, Yamaha*, Kawasaki*, Suzuki* and Husqvarna. Recommended for separate-sump applications, including the Honda CRF, and many two-stroke dirt bikes. JASO MA; API SG, SJ, SH, SL.


AMSOIL Synthetic Dirt Bike Oil should be changed according to the vehicle manufacturer’s recommendations.

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AMSOIL products are backed by a Limited Liability Warranty. For complete information visit www.amsoil.com/warranty.aspx.

This product is not expected to cause health concerns when used for the intended applications and according to the recommendations in the Safety Data Sheet (SDS). An SDS is available via the Internet at www.amsoil.com or upon request at (715) 392-7101. Keep Out of Reach of Children. Recycle used oil and bottle.



Kinematic Viscosity @ 100°C, cSt (ASTM D445) 14.2
Kinematic Viscosity @ 40°C, cSt (ASTM D445) 93.5
Viscosity Index (ASTM D2270) 156
Pour Point °C (°F) (ASTM D97) -44 (-47)
Flash Point °C (°F) (ASTM D92) 246 (475)
Fire Point °C (°F) (ASTM D92) 254 (489)
Noack Volatility, % weight loss (g/100g) (ASTM D5800)4.0
High Temperature/High Shear Viscosity @ 150°C , 1.0 x 106 s-1, cP (ASTM D4683)4.1

Dirt Bile Oil Reviews from AMSOIL customers

Air cooled Honda XR400R, 25 years old, runs like new

By  MXrider,  a  Verified Buyer  from  Tucson AZ  on  August 02, 2022

I’ve been running AMSOIL in my XR400R for 25 years and just checked the compression, 11 PSI off factory spec. It runs in the Arizona desert and engine temp is normally high (220), its an air-cooled bike and heat dissipation is everything.. I think AMSOIL adds Unicorn pee or something magic, that’s the only way this is possible…
Best oil on the market
By  MATHEW,  a  Verified Buyer  on  May 19, 2022
This is absolutely the best oil on the market
Hard shifting in trans
By  JAMIE,  a  Verified Buyer  on  April 25, 2022
2020 crf450r was having a hard shifting issue 1st and 2nd gear. Decided to change from Honda GN4 to Amsoil. On very first ride big difference in trans shifting and has only gotten better. I am now a true believer in Amsoil Products
By  Coop,  a  Verified Buyer  from  Okotoks  on  February 28, 2022
Works like a charm on all my wet clutch bikes. Shifts are smooth and suhweet!
Excellent Lubrication
By  Danny,  a  Verified Buyer  from  Southern California   on  February 14, 2022
Excellent lubrication, the oil is super slick even when it’s time to change. I use this in my motorcycle and wish I’d had it many times before. I used to use Lucas, while it’s not a bad oil (at least I don’t think it is) I figured Id give Amsoil a shot, and at least to say, I’m not looking back. My bike shifts smoother actually runs slightly cooler and just feels better all-around in general. I’m all about reliability and so far I’m sold. Great stuff, only downfall is it’s a little pricey, but I guess you pay for what you get and good things don’t come cheap. Going to try it in my truck next time around. I would recommend this product to anyone who is looking for the best product with the rest and reassurance that you’re putting good stuff in your machine.
Best dirt bike oil available
By  WILLIAM,  a  Verified Buyer  from  Michigan  on  July 20, 2021
This oil makes the engine run better seems to make more horsepower and better gas mileage. Is very clean when you do a change also.

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