MAMMOTH PETROLEUM
778-370-3330
Automotive Gear Oil GL-4 is a high-quality, multi-purpose gear lubricant specifically engineered for use in manual transmissions, transaxles, and steering gears that require an API GL-4 level of protection. Unlike standard GL-5 oils which can be chemically aggressive toward "yellow metals," this formulation is "synchronizer-safe," meaning it will not corrode or prematurely wear the brass, bronze, or copper components essential for smooth shifting. It is formulated with premium paraffinic base oils and a balanced extreme-pressure (EP) additive package that provides a high-strength film to protect gear teeth under heavy loads. With excellent thermal stability and resistance to oxidation, it prevents the buildup of sludge and varnish, ensuring a clean internal environment. It is the professional choice for vintage and modern manual drivetrains where shifting precision and component longevity are the primary operational goals.
PRODUCT RESOURCES
PERFORMANCE
Optimized friction characteristics ensure smooth, crisp gear engagement and "shift-feel" in manual transmissions.
Maintains stable viscosity across a wide temperature range for consistent performance in all seasons.
Reduces internal fluid drag to improve drivetrain efficiency and cooling.
PROTECTION
Formulated with "yellow-metal safe" chemistry to protect brass and bronze synchronizer rings.
Provides a robust lubricating film that guards against gear tooth scoring and abrasive wear.
Fortified with high-tier rust and corrosion inhibitors to shield internal surfaces from moisture damage.
UPTIME
Prevents the formation of sludge and varnish that can lead to stiff shifting and mechanical binding.
Extended oxidation stability allows for longer service intervals and reduced maintenance labor.
Excellent seal compatibility prevents oil loss and protects the integrity of the transmission housing.
COMPOSITION
RESISTANCE
PROTECTION
FEATURES & BENEFITS
Synchronizer Safe: Specifically engineered to be non-aggressive toward copper-based alloys.
EP Load Shield: Provides high-pressure protection for gear sets without sacrificing shifting smoothness.
Thermal Durability: Resists oil thickening and thermal breakdown during high-heat operation.
Foam Resistance: Formulated to stay stable and bubble-free for consistent lubrication at high RPMs.
APPLICATIONS
Manual transmissions and transaxles in passenger cars, SUVs, and light trucks requiring GL-4.
Automotive steering gears and universal joints.
Vintage and classic car gearboxes where GL-5 additives may be too aggressive for older components.
MAMMOTH TECHNICAL TIP:
This is a critical distinction for your shop. Many people think GL-5 is "better" than GL-4, but if you put a modern GL-5 into an older manual transmission with brass synchronizers, the sulfur-phosphorus additives can actually eat the yellow metal over time. For a smooth, long-lasting manual gearbox, stick to the GL-4—it’s designed to protect the "soft" parts just as much as the steel gears.