V-Twin heat. Wet-clutch compatibility. Dirt-bike dust.
Air-cooled V-Twins bake the sump past 220 °F at an idle; metric sport bikes and dirt bikes share oil with the clutch; both punish conventional car motor oil. AMSOIL's motorcycle and powersports lines are engineered for those exact duty cycles, and every order rides through the dealer referral so Preferred Customer pricing applies at checkout.
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Three lines for V-Twin, metric, and dirt bike.
Pick the line that matches your platform — each one is tuned to the duty cycle that line actually sees. Click through to amsoil.com to confirm fitment; Preferred Customer pricing rides along on the dealer referral tag so the price at checkout is the dealer rate.
V-Twin 20W-50
AMSOIL’s 100% synthetic V-Twin engine oil — formulated for air-cooled Harley-Davidson, Indian, and metric V-Twin platforms. The synthetic base stock holds film strength when sump temperatures climb past 220 °F at idle in summer traffic, and the additive system is balanced to protect flat-tappet cams without loading the clutch.
Best for: air-cooled V-Twins, baggers, cruisers, big-twin customs.
Shop on AMSOILSynthetic Motorcycle 10W-40
JASO MA / MA2 wet-clutch compatible 100% synthetic motorcycle oil — friction modifiers are tuned so clutch plates engage without slipping. The 10W-40 viscosity is the factory fill for the sport bike and ADV platforms most common on Central WA backroads, and the additive package resists the fuel dilution that comes from repeated short-trip commuting.
Best for: metric sport bikes, ADV, standards, anything with a wet clutch.
Shop on AMSOILDirt Bike 10W-40
AMSOIL’s synthetic dirt bike engine oil — built for 4-stroke off-road platforms where the engine and the transmission share the sump. The film strength holds up over jumps and sustained high-RPM pulls; the additive system tolerates the dust ingestion and short-trip starts that punish conventional oil on a trail day.
Best for: 4-stroke dirt bikes, dual-sport, enduro, late-model ATV/UTV.
Shop on AMSOILBuilt for the cycle that car motor oil can't handle.
Air-cooled V-Twin heat, a shared wet clutch, and the dust ingestion of a trail day each punish the oil in a different way. AMSOIL's motorcycle lines address all three with the same full-synthetic base stock and platform-tuned additive packages.
V-Twin sump past 220 °F
Air-cooled V-Twin oil-pan temperatures run past 220–250 °F at idle in summer traffic. Conventional car motor oil thins out and loses film strength in that window; the V-Twin synthetic base stock holds viscosity so bearings, cam lobes, and pistons stay separated when the oil is hottest — and it cools down cleanly without leaving varnish.
JASO MA / MA2 friction modifiers
The motorcycle shares one sump with the wet clutch. AMSOIL's friction modifiers are tuned so the clutch plates engage without slipping; standard car motor oil — with too much ZDDP for flat-tappet protection — glazes the plates and turns a wet clutch into a slipping one within a few thousand miles. JASO MA / MA2 certification is the measurable difference.
Holds TBN through dust ingestion
Trail days and daily-driver short trips never let the oil fully cook off condensation or blow-by; dirt-bike platforms add dust ingestion on top of that. The Synthetic Motorcycle and Dirt Bike synthetics are built to resist fuel dilution and hold total base number (TBN) across the drain interval, so the oil keeps its alkalinity reserve instead of dropping into acid wear territory before the change.
Drain interval depends on platform and duty cycle — the dealer adapts the recommendation to your actual riding pattern on request. JASO MA / MA2 certification covers every recommended motorcycle line.
Ready to enroll through the dealer referral?Pricing comes from AMSOIL — not added by the dealer.
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