AMSOIL 10W-40 Synthetic Dirt Bike Oil
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Designed to Improve Bike and Rider Performance
AMSOIL 10W-40 Synthetic Dirt Bike Oil is specifically engineered to provide superior clutch engagement and engine reliability in severe conditions, making it the best choice for professional riders and weekend warriors focused on improving performance on the trail or track.
Key Benefits
- Consistent clutch feel after 32 simulated race starts (OEM failed at 16)
- Clutch plates remained clean with no discoloration or wear
- Resists mechanical shear and viscosity loss under high RPM
- Premium anti-wear additives protect gears, bearings and pistons
- Maximizes horsepower with reduced friction
- Recommended for Honda CRF and two-stroke separate-sump applications
- Extensively tested by professional riders in race bikes
- Warranty Secure — keeps factory warranty intact
Consistent Clutch Feel from Start to Finish
In extreme testing, AMSOIL Synthetic Dirt Bike Oil continued to deliver consistent clutch engagement following 32 simulated race starts, while a leading OEM oil demonstrated inconsistent clutch-lever action and poor clutch engagement after only 16 starts. The clutch plates lubricated with AMSOIL remained clean and in good condition, while the OEM oil plates revealed discoloration and wear.
The synthetic base oils naturally resist mechanical shear and viscosity loss, maintaining a thick protective film that helps prevent metal-to-metal contact under high-RPM operation and extreme heat. Premium anti-wear additives provide extra protection against gear, bearing and piston wear.
Technical Specifications
| Property | Value |
|---|---|
| Kinematic Viscosity @ 100°C, cSt | 14 |
| Kinematic Viscosity @ 40°C, cSt | 86.4 |
| Viscosity Index | 167 |
| Flash Point | 240°C (464°F) |
| Fire Point | 270°C (518°F) |
| Pour Point | -40°C (-40°F) |
| NOACK Volatility, % weight loss | 4.8 |
| HT/HS Viscosity @ 150°C, cP | 4.0 |
| Four-Ball Wear Test Scar, mm | 0.57 |
| Foam (Sequence I, II, III) | 0/0, 20/0, 0/0 |
| Total Base Number | 7.6 |
Industry Certifications & OEM Approvals
JASO
- MA
API
- SG, SJ, SH, SL
Applications & Specifications
Use 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
Change according to the vehicle manufacturer's recommendations.
Pros and Cons
Pros
- Consistent clutch feel after 32 simulated race starts (OEM failed at 16)
- Clutch plates remained clean with no discoloration or wear
- Resists mechanical shear and viscosity loss under high RPM
- Premium anti-wear additives protect gears, bearings and pistons
- Maximizes horsepower with reduced friction
- Recommended for Honda CRF and two-stroke separate-sump applications
- Extensively tested by professional riders in race bikes
- Warranty Secure — keeps factory warranty intact
Cons
- Premium Investment: Higher initial cost compared to conventional or "shelf-brand" synthetic oils.
- Limited Local Retail: Primarily available through authorized dealers and specialized synthetic outlets. National Synthetics is a local stocking dealer. Call 1-678-944-8816 to confirm in-stock items for same-day local pickup.
Order Through Your Independent AMSOIL Dealer
Give your dirt bike the competitive edge. As your Independent AMSOIL Dealer, we provide expert guidance and competitive pricing on all AMSOIL products.
Independent AMSOIL Dealer #30576570
Shipping & Returns
Fast, Reliable Shipping
- Free standard ground shipping on orders of $100 ($130 in Canada) or more.
- Orders under the threshold ship for a flat $9.99 ($12.99 in Canada) freight charge.
- In-stock items typically delivered in two to three business days.
- U.S. and Canada only — no shipments to PO Boxes.
30-Day Return Policy
- Return unopened, currently marketed products within 30 days for a full refund (minus freight).
- Exchange unopened products within 90 days with no restocking fee.
- Special-order items are non-returnable.
- Returns are handled directly by AMSOIL.
Frequently Asked Questions
Yes. AMSOIL 10W-40 Synthetic Dirt Bike Oil is recommended for the Honda CRF and many other separate-sump dirt bike applications that require 10W-40 motorcycle oil.
In extreme simulated-start testing, AMSOIL Synthetic Dirt Bike Oil delivered consistent clutch engagement after 32 starts, while a leading OEM oil showed inconsistent clutch-lever action after only 16 starts. The AMSOIL-lubricated clutch plates remained clean with no discoloration, while the OEM plates showed wear.
Customer Reviews
See all 183 reviews10W-40 dirt bike oil
Great product, been using this on a 2024 Honda CRF150R since new. Changed regularly due to racing the bike. Seems to hold up very well. Will continue to use it.
Independent AMSOIL Dealer #30576570. Product information sourced from AMSOIL. Visit AMSOIL.com for the most current product details and availability.