Motocross · Off-Road · Enduro · Trail

AMSOIL Dirt Bike Oil — 4-Stroke, 2-Stroke, Trans, Suspension & Fuel

JASO MA2 four-stroke engine oil in 10W-40, 10W-50 and 10W-60. DOMINATOR 2-stroke racing oil. Dedicated SAE 80 gearbox fluid, Shock Therapy fork & shock fluid, octane boost, and fuel stabilizer — purpose- built for Honda CRF, Yamaha YZ, Kawasaki KX, KTM, Husqvarna, GASGAS, and Beta.

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Why MX Bikes Need a Purpose-Built Synthetic

Few engines work harder than a modern four-stroke motocross bike. Wide-open throttle, sustained redline RPM, brutal heat, and a shared engine-and-clutch oil sump make this one of the most demanding lubrication environments anywhere. The AMSOIL Synthetic Dirt Bike Oil lineup — 10W-40, 10W-50, and 10W-60 — is built for it.

JASO MA2 certified — consistent wet-clutch feel
Exceptional shear stability under extreme RPM
Full 4-stroke lineup: 10W-40, 10W-50 & 10W-60
DOMINATOR 2-stroke racing oil — pre-mix or injection
Dedicated SAE 80 transmission fluid for 2-stroke gearboxes
Compatible with Honda, Yamaha, Kawasaki, Suzuki
Compatible with KTM, Husqvarna, GASGAS, and Beta
Resists viscosity breakdown in deep sand & desert heat
Anti-friction, anti-scuff chemistry for max power
Made in the USA — backed by AMSOIL Limited Warranty

AMSOIL 4-Stroke Dirt Bike Engine Oil

Three viscosities of 100% synthetic, JASO MA2 wet-clutch certified four-stroke MX and off-road oil — engineered for the brutal heat, redline RPM, and aggressive clutch action of motocross. Covers Honda CRF, Yamaha YZ-F/WR-F, Kawasaki KX-F, Suzuki RM-Z, KTM SX-F/EXC-F, Husqvarna FC/FE, GASGAS MC-F, and Beta RR.

AMSOIL 10W-40 100% Synthetic Dirt Bike Oil

The most-used viscosity in motocross. Confident clutch feel, excellent wear protection, and superior shear stability for four-stroke MX and off-road bikes from Honda CRF, Yamaha YZ/WR, Kawasaki KX, Suzuki RM-Z, KTM SX-F, Husqvarna FC, GASGAS, and Beta.

Viscosities:

10W-40

AMSOIL Product Codes:

• DB40QT-EA (1 qt)
• DB401G-EA (1 gal)

Specifications:

• JASO MA2
• API SL
• Wet-clutch certified
• 100% synthetic

Service interval: Race: every moto · Trail: 5–10 hours

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AMSOIL 10W-50 100% Synthetic Dirt Bike Oil

Heavier viscosity for high-output four-strokes, big-bore builds, and hot-weather riding. Extra film strength for engines running at sustained high RPM in deep sand, mud, and desert heat. JASO MA2 wet-clutch certified.

Viscosities:

10W-50

AMSOIL Product Codes:

• DB50QT-EA (1 qt)
• DB501G-EA (1 gal)

Specifications:

• JASO MA2
• API SL
• Hot-climate / big-bore
• Wet-clutch certified

Service interval: Race: every moto · Trail: 5–10 hours

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AMSOIL 10W-60 100% Synthetic Dirt Bike Oil

Heaviest dirt bike viscosity for the most demanding four-stroke applications — KTM, Husqvarna, and GASGAS factory recommendations, big-bore race builds, and extreme-heat conditions. Maximum film strength and wear protection at sustained redline RPM.

Viscosities:

10W-60

AMSOIL Product Codes:

• DB60QT-EA (1 qt)
• DB601G-EA (1 gal)

Specifications:

• JASO MA2
• API SL
• KTM / Husqvarna / GASGAS factory spec
• Maximum film strength

Service interval: Race: every moto · Trail: 5–10 hours

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DOMINATOR® 2-Stroke Racing Oil & Transmission Fluid

Premium two-stroke pre-mix/injection oil and dedicated SAE 80 transmission fluid for sealed two-stroke gearboxes. The proven combination for KTM, Husqvarna, Yamaha YZ, GASGAS, and Beta two-strokes — anti-scuff chemistry, clean burn, crisp shifts.

AMSOIL DOMINATOR® 100% Synthetic 2-Stroke Racing Oil

Premium pre-mix and injection oil for two-stroke motocross, off-road, and racing engines. Anti-friction, anti-scuff chemistry delivers maximum power, low smoke, and exceptional protection for high-output two-strokes from KTM, Husqvarna, Yamaha YZ, GASGAS, and Beta.

AMSOIL Product Codes:

• TDRQT-EA (1 qt)
• TDR1G-EA (1 gal)

Specifications:

• API TC
• JASO FD
• ISO-L-EGD
• Pre-mix or injection

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AMSOIL 100% Synthetic Dirt Bike Transmission Fluid (SAE 80)

Dedicated SAE 80 transmission and clutch fluid for two-stroke dirt bikes with separate transmission sumps. Crisp shifting and consistent clutch feel race after race — helps prevent slip or grab during aggressive engagement.

Viscosities:

SAE 80

AMSOIL Product Codes:

• DBTFQT-EA (1 qt)

Specifications:

• Dedicated 2-stroke gearbox fluid
• Crisp shift feel
• Consistent clutch engagement

Service interval: Race: every 3–5 motos · Trail: 10–15 hours

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Shock Therapy® Suspension Fluid

100% synthetic fork and shock fluid that resists foaming, fade, and viscosity loss — keeps damping consistent from the first lap to the last. Two viscosities cover the most common dirt bike fork and shock specifications.

AMSOIL Shock Therapy® Suspension Fluid #5 Light

Premium synthetic suspension fluid for dirt bike forks and shocks requiring a light viscosity. Delivers consistent damping, smooth action, and resistance to foaming and fade — keeps your suspension feeling fresh moto after moto.

Viscosities:

#5 Light

AMSOIL Product Codes:

• STLQT-EA (1 qt)
• STL1G-EA (1 gal)

Specifications:

• Most modern MX fork spec
• Resists foaming and fade
• Consistent damping

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AMSOIL Shock Therapy® Suspension Fluid #10 Medium

Premium synthetic suspension fluid in a medium viscosity for dirt bike forks and shocks. Maintains consistent damping characteristics across temperature swings, resists foaming, and extends rebuild intervals.

Viscosities:

#10 Medium

AMSOIL Product Codes:

• STMQT-EA (1 qt)
• STM1G-EA (1 gal)

Specifications:

• Common shock fluid spec
• Temperature stable
• Extends rebuild intervals

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Motorcycle Fuel Additives

Round out your dirt bike service kit with AMSOIL Motorcycle Octane Boost for high-compression four-strokes, Gasoline Stabilizer for off-season storage, and Quickshot for ethanol-related fuel issues and short-term storage between rides.

AMSOIL Motorcycle Octane Boost

Boosts gasoline octane for improved power, smoother performance, and reduced engine knock and ping. Formulated specifically for motorcycle and powersports four-stroke engines — ideal for high-compression dirt bikes running pump fuel.

AMSOIL Product Codes:

• MOBCN-EA (4 fl oz)

Specifications:

• Reduces engine knock
• Improves throttle response
• High-compression 4-stroke MX

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AMSOIL Gasoline Stabilizer

Keeps fuel fresh up to 12 months for off-season storage. Prevents gum, varnish, and corrosion in fuel systems — essential for dirt bikes that sit between riding seasons or get stored over winter.

AMSOIL Product Codes:

• ASTCN-EA (8 fl oz)
• AST16-EA (16 fl oz)

Specifications:

• Up to 12-month storage
• Prevents gum & varnish
• Carb & injector safe

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AMSOIL Quickshot® Gasoline Treatment and Stabilizer

Fast-acting fuel system cleaner and stabilizer for ethanol-related performance issues. Restores peak performance, addresses water-related problems, and stabilizes fuel during short-term storage. Excellent for dirt bikes that see intermittent use.

AMSOIL Product Codes:

• AQSCN-EA (5.25 fl oz)

Specifications:

• Ethanol fuel treatment
• Cleans injectors / carbs
• Short-term storage stabilizer

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Dirt Bike Application Selector

Match your dirt bike to the recommended AMSOIL engine and gearbox fluids. For exact part numbers by year, make, and model, also see the AMSOIL Motorcycle Lookup tool.

Application	Recommended AMSOIL	Service Interval	Notes
Honda CRF250R / CRF450R / CRF250RX / CRF450RX	10W-40 (DB40) — heat: 10W-50 (DB50)	Every moto / 5 hr trail	JASO MA2 + API SL. Honda factory spec 10W-40.
Honda CRF250F / CRF300L / Trail (CRF150F)	10W-40 (DB40)	5–10 hours	Recreational trail four-stroke.
Yamaha YZ250F / YZ450F / WR250F / WR450F	10W-40 (DB40) — heat / big-bore: 10W-50 (DB50)	Every moto / 5 hr trail	Yamaha factory spec 10W-40.
Yamaha YZ125 / YZ250 (2-stroke)	DOMINATOR (TDR) pre-mix + Trans Fluid (DBTF)	Trans: every 3–5 motos	Pre-mix ratio per owner's manual (typically 32:1–50:1).
Kawasaki KX250 / KX450 (4-stroke) / KX250X / KX450X	10W-40 (DB40)	Every moto / 5 hr trail	Kawasaki factory spec 10W-40.
Kawasaki KLX 230 / 300 / 450R / KLR / Recreation	10W-40 (DB40)	5–10 hours	Trail / dual-sport four-stroke.
Suzuki RM-Z250 / RM-Z450	10W-40 (DB40)	Every moto / 5 hr trail	Suzuki factory spec 10W-40.
KTM 250 SX-F / 350 SX-F / 450 SX-F / EXC-F	10W-50 (DB50) or 10W-60 (DB60)	Every moto / 5 hr trail	KTM factory typically lists 10W-50 / 10W-60.
KTM 125 SX / 250 SX / 300 XC (2-stroke)	DOMINATOR (TDR) pre-mix + Trans Fluid (DBTF)	Trans: every 3–5 motos	Premium pre-mix at owner's manual ratio.
Husqvarna FC 250/350/450 / FE 350/501	10W-50 (DB50) or 10W-60 (DB60)	Every moto / 5 hr trail	Same engine family as KTM — 10W-50 / 10W-60.
Husqvarna TC / TE 125-300 (2-stroke)	DOMINATOR (TDR) + Trans Fluid (DBTF)	Trans: every 3–5 motos	Pre-mix two-stroke MX / enduro.
GASGAS MC 250F / 450F / EX 250F / 450F	10W-50 (DB50) or 10W-60 (DB60)	Every moto / 5 hr trail	KTM family engine spec.
GASGAS MC 125 / 250 / 300 (2-stroke)	DOMINATOR (TDR) + Trans Fluid (DBTF)	Trans: every 3–5 motos	Premium pre-mix and dedicated gearbox fluid.
Beta RR 4T 350/390/430/480 / Xtrainer	10W-50 (DB50) or 10W-60 (DB60)	Per Beta service	Italian enduro four-stroke — heavier viscosity.
Beta RR 2T 125/200/250/300	DOMINATOR (TDR) + Trans Fluid (DBTF)	Trans: every 3–5 motos	Premium two-stroke racing oil.

10W-40 vs. 10W-50 vs. 10W-60 — 4-Stroke MX Oil

All three AMSOIL 4-stroke dirt bike oil viscosities are JASO MA2 wet-clutch certified. Match the grade to your OEM specification, climate, and engine build.

Feature	10W-40 (DB40)	10W-50 (DB50)	10W-60 (DB60)
Best for	Most modern Japanese MX 4-strokes	Hot climate, big-bore, deep sand	KTM / Husqvarna / GASGAS factory spec
Product code	DB40	DB50	DB60
JASO rating	MA2	MA2	MA2
API rating	SL	SL	SL
Cold-start flow	Excellent	Very good	Good
Hot-running film strength	Strong	Stronger	Strongest
Wet-clutch friendly	Yes	Yes	Yes

Best Synthetic Oil for Motocross and Off-Road Dirt Bikes

Few engines work harder than a modern four-stroke motocross bike. Wide-open throttle, sustained redline RPM, brutal heat, and a shared engine-and-clutch oil sump make this one of the most demanding lubrication environments anywhere. The AMSOIL Synthetic Dirt Bike Oil lineup — 10W-40 (DB40), 10W-50 (DB50), and 10W-60 (DB60) — is built for it.

10W-40 (DB40) — The Standard Motocross Viscosity

Honda CRF, Yamaha YZ-F and WR-F, Kawasaki KX-F, Suzuki RM-Z — virtually every modern Japanese four-stroke MX and off-road bike specifies 10W-40. AMSOIL 10W-40 100% Synthetic Dirt Bike Oil delivers the JASO MA2 friction profile riders trust for crisp clutch engagement.

10W-50 (DB50) — Hot Weather and Big-Bore Builds

If you ride summer in Florida or the desert, run a 350-to-500cc big-bore kit, or hold the throttle pinned in deep sand, the 10W-50 grade gives you extra film strength when oil temperatures climb past 250 °F.

10W-60 (DB60) — KTM, Husqvarna, GASGAS & Extreme Conditions

KTM, Husqvarna, and GASGAS factory specs frequently call for a 10W-60 grade. AMSOIL 10W-60 100% Synthetic Dirt Bike Oil is the heaviest viscosity in the lineup — engineered for maximum film strength under the most extreme heat and sustained high-RPM operation.

DOMINATOR® 2-Stroke Racing Oil

For two-stroke MX and off-road bikes, AMSOIL DOMINATOR 100% Synthetic 2-Stroke Racing Oil ( TDR) is the proven choice. Pre-mix or oil-injection compatible, with anti-friction and anti-scuff chemistry that delivers maximum power and clean burn for KTM, Husqvarna, Yamaha YZ, GASGAS, and Beta two-strokes.

Two-Stroke Transmission Fluid (DBTF)

Two-stroke dirt bikes have a sealed gearbox that runs a dedicated transmission fluid — never engine oil. AMSOIL 100% Synthetic Dirt Bike Transmission Fluid SAE 80 (DBTF) keeps shifting crisp and clutch feel consistent through long motos and trail rides.

Gasoline Additives for Dirt Bikes

Pump fuel is the enemy of stored dirt bikes. AMSOIL Gasoline Stabilizer (AST) keeps fuel fresh up to 12 months — critical for off-season storage. AMSOIL Quickshot (AQS) is the go-to for ethanol-related performance issues, water in the fuel, and short-term storage. AMSOIL Motorcycle Octane Boost (MOB) raises pump-gas octane to eliminate knock and unlock full power on high-compression four-stroke MX engines.

Shock Therapy® Suspension Fluid

Suspension performance is everything on a dirt bike. AMSOIL Shock Therapy Suspension Fluid #5 Light (STL) and #10 Medium (STM) are premium synthetic fork and shock oils engineered to resist foaming, fade, and viscosity loss. Damping stays consistent lap after lap.

AMSOIL vs. Maxima Pro Plus, Motul 7100 Off-Road, Bel-Ray EXS & Yamalube

AMSOIL Synthetic Dirt Bike Oil is independently tested against Maxima Pro Plus, Motul 7100 4T Off-Road, Bel-Ray EXS Full-Synthetic, Yamalube Full Synthetic, and Honda HP4M — and consistently demonstrates superior wear protection, higher film strength under extreme heat, and better shear stability through extended motos.

Dirt Bike Oil for Florida, Tampa Bay & the United States

1stSynthetic.com is your independent AMSOIL Dealer based in Dade City, Florida, serving MX and off-road riders across Tampa, Lakeland, Wesley Chapel, Zephyrhills, Brooksville, Brandon, Sarasota, Orlando, and the entire United States. Order online and ship direct from the AMSOIL distribution center, or join the Preferred Customer program to save 25% on every dirt bike order, every time.

Dirt Bike Oil FAQ

What is the best oil for a four-stroke dirt bike?▾

AMSOIL 10W-40 100% Synthetic Dirt Bike Oil (DB40QT-EA) is the most-recommended choice for four-stroke MX and off-road bikes. It is JASO MA2 certified for confident wet-clutch engagement and engineered for the brutal heat, high RPM, and short oil intervals of motocross.

When should I use 10W-50 instead of 10W-40 dirt bike oil?▾

Choose AMSOIL 10W-50 100% Synthetic Dirt Bike Oil (DB50QT-EA) if you ride in extreme heat, run a big-bore engine, ride deep sand or technical hill climbs, or hold the throttle pinned for long pulls. The heavier weight maintains film strength when oil temperatures spike past 250 °F.

Who should use AMSOIL 10W-60 Dirt Bike Oil?▾

AMSOIL 10W-60 100% Synthetic Dirt Bike Oil (DB60QT-EA) is built for the most extreme four-stroke applications — KTM, Husqvarna, and GASGAS models that specify a 10W-60 grade, big-bore race builds, and riders facing the highest sustained engine temperatures.

What is the best oil for a two-stroke motocross or off-road bike?▾

AMSOIL DOMINATOR 100% Synthetic 2-Stroke Racing Oil (TDRQT-EA) is engineered for high-output two-stroke MX, off-road, and racing engines. It can be used as pre-mix or in oil-injection systems and delivers maximum power, anti-scuff protection, and clean burn for KTM, Husqvarna, Yamaha YZ, GASGAS, and Beta two-strokes.

Do I need a separate oil for my two-stroke transmission?▾

Yes. Two-stroke dirt bikes have a sealed transmission and clutch sump that does not share oil with the engine. AMSOIL 100% Synthetic Dirt Bike Transmission Fluid SAE 80 (DBTFQT-EA) is purpose-formulated for this gearbox — never use engine oil there.

How often should I change dirt bike oil?▾

Race riders often change oil after every moto. Trail and recreation riders typically change every 5 to 10 hours of operation. AMSOIL synthetic chemistry resists shear and contamination far better than petroleum oils, but dirt bikes work hard — change often regardless of brand.

Will AMSOIL dirt bike oil cause clutch slip?▾

No. Every AMSOIL four-stroke dirt bike oil (DB40, DB50, DB60) is JASO MA2 certified, the highest motorcycle friction standard for wet-clutch engines. It is specifically formulated to deliver positive, consistent clutch engagement — not to cause slip.

Should I use a fuel stabilizer in my dirt bike?▾

Yes. Dirt bikes often sit for weeks or months between rides, and pump gasoline starts breaking down in as little as 30 days. AMSOIL Gasoline Stabilizer (ASTCN-EA) keeps fuel fresh up to 12 months, while AMSOIL Quickshot (AQSCN-EA) addresses ethanol-related issues and short-term storage. Both prevent gum, varnish, and hard-starting problems.

Does AMSOIL Motorcycle Octane Boost really help dirt bikes?▾

Yes — especially for high-compression four-stroke MX engines that prefer premium fuel. AMSOIL Motorcycle Octane Boost (MOBCN-EA) raises octane to reduce knock and ping, smooth out throttle response, and let the engine make full power on pump gas.

Which Shock Therapy suspension fluid should I use — #5 Light or #10 Medium?▾

Use the viscosity recommended by your fork or shock manufacturer. Most modern dirt bike forks call for a #5 Light fluid (STLQT-EA), while many shocks use #10 Medium (STMQT-EA). AMSOIL Shock Therapy resists foaming and viscosity loss so damping stays consistent from the first lap to the last.

How often should I change dirt bike fork and shock fluid?▾

Race riders typically service forks every 15–30 hours and shocks every 30–50 hours. Trail and recreation riders can extend that, but contaminated or sheared suspension fluid causes harsh, inconsistent damping. AMSOIL Shock Therapy synthetic chemistry holds up far longer than conventional suspension oil.

Where can I buy AMSOIL dirt bike oil in Florida?▾

1stSynthetic.com is your independent AMSOIL Dealer based in Dade City, Florida — serving MX riders across Tampa, Lakeland, Wesley Chapel, Zephyrhills, Brooksville, and customers throughout the United States. Order online, ship direct from the AMSOIL distribution center, or join the Preferred Customer program to save 25% on every dirt bike order.

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