BRIGGS & STRATTON SYNTHETIC 4T RACING OIL

AMSOIL Briggs & Stratton Synthetic 4T Racing Oil delivers maximum horsepower and durable wear protection in a single formulation, purpose-built for the unique demands of small-displacement, air-cooled four-stroke racing engines used in kart, junior drag, and quarter midget competition.

Air-cooled racing engines operate in a brutal environment. They spin at sustained high RPMs, rely on splash lubrication in many configurations, and generate extreme heat with limited cooling capacity. Automotive oils aren't designed for this. PAG-based and conventional mineral karting oils fall short too, either sacrificing protection for power or leaving horsepower on the table with excessive viscosity drag. The oil in these engines has to do more with less, and it has to do it consistently from green flag to checkered flag.

MAXIMIZES HORSEPOWER WITHOUT SACRIFICING WEAR PROTECTION
Most racers face a tradeoff: run a lighter oil to free up power, or run a heavier oil to keep the engine alive. Synthetic 4T Racing Oil eliminates that compromise. Specialized friction modifiers and advanced additives reduce energy loss due to internal friction, giving racers the horsepower characteristics of a lite oil combined with the film strength and wear resistance of a heavier one. In ASTM D4172 Four-Ball Wear testing at 40 kg load, 75°C, and 1200 rpm for one hour, Synthetic 4T Racing Oil produced a wear scar of just 0.36 mm, confirming strong anti-wear performance under load. More power to the ground, less wear on the engine.

HANDLES THE EXTREME HEAT OF AIR-COOLED RACING ENGINES
Air-cooled Briggs & Stratton racing engines can push oil temperatures well beyond what a typical automotive oil is formulated to handle. Synthetic 4T Racing Oil is built on pure synthetic base oils that resist thermal breakdown far better than conventional alternatives. It posts a NOACK Volatility result of just 9.7% weight loss (ASTM D5800), meaning it resists evaporative burn-off and maintains its protective qualities at elevated temperatures. The flash point of 226°C (439°F) and fire point of 244°C (471°F) further underscore its thermal stability. Reduced thermal breakdown means fewer sludge and deposit problems, which translates directly to sustained compression and consistent power output over the life of the engine.

RESISTS FOAM AT HIGH RPM
Splash-lubricated engines are particularly prone to oil foaming, especially at the elevated RPMs common in kart racing and other small-engine competition. Foam introduces air into the oil film, reducing its ability to protect moving parts and carry heat away from critical surfaces. Synthetic 4T Racing Oil is engineered with powerful anti-foam agents that maintain a durable, consistent lubricating film even under the most aggressive operating conditions.

PROTECTS AGAINST CORROSION BETWEEN RACES
Racing engines often sit idle between events, sometimes for weeks. Moisture accumulation during storage can lead to corrosion on internal engine surfaces. Synthetic 4T Racing Oil contains dedicated corrosion inhibitors that guard against rust formation during downtime, so the engine is ready to perform when it hits the track again.

STRONG VISCOMETRIC PROPERTIES ACROSS A WIDE TEMPERATURE RANGE
With a viscosity index of 156, Synthetic 4T Racing Oil maintains stable viscosity across a broad operating temperature range. Its high-temperature/high-shear viscosity of 4.2 cP at 150°C (ASTM D5481) confirms that it holds its protective film under the most demanding thermal and mechanical stress. A pour point of -46°C (-51°F) means it flows freely in cold conditions, though most racers will care more about what happens at the top of the temperature range.

APPLICATIONS AND COMPATIBILITY
Synthetic 4T Racing Oil is recommended for stock and modified small-displacement air-cooled racing engines, including Briggs & Stratton single-cylinder and V-Twin competition engines. It works in both splash-lubricated and pressure-lubricated configurations and is compatible with gasoline and alcohol fuels. When converting from another oil, do not mix. Drain the existing oil completely, refill with Synthetic 4T Racing Oil, run the engine at idle to low speed for 2-3 minutes, then drain and refill again. Compatible with mineral oils.

SERVICE LIFE
Follow the original equipment manufacturer or engine builder recommendations for oil change intervals.