Engine Oil (Gasoline Engine)

Engine oil with the American Petroleum Institute Certified for Gasoline Engines starburst symbol of the proper viscosity. To determine the preferred viscosity for your vehicle's engine, see Engine Oil .

Engine Oil (DURAMAX Diesel Engine)

Engine oil with the letters CI-4 or CH--4 is best for your vehicle. The CI--4 or CH--4 designation may appear either alone or in combination with other API designations, such as API CI--4/SL. These letters show American Petroleum Institute levels of quality. To determine the preferred viscosity for your vehicle's diesel engine, see Engine Oil .

Engine Oil (Caterpillar Diesel Engine)

See the Caterpillar Operation & Maintenance Manual for engine oil recommendations.

Engine Coolant (Caterpillar Diesel Engine)

See the Caterpillar Operation & Maintenance Manual for engine coolant recommendations.

Engine Coolant (Gasoline Engine & DURAMAX Diesel)

50/50 mixture of clean, drinkable water and use only DEX-COOL Coolant. See Engine Coolant .

Hydraulic Brake System

Delco Supreme 11 Brake Fluid or equivalent DOT-3 brake fluid.

Windshield Washer Solvent

GM Optikleen Washer Solvent or equivalent.

Clutch Bearing Lubricant

Clutch Bearing Lubricant (GM Part No. 12378484 or equivalent NLGI #3 consistency).

Exhaust Brake Ball Joint Cap Lubricant

High--Temperature Grease (GM Part No. U.S. 1051344, in Canada 903037, or equivalent) or NLGI #3 consistency.

Power Steering System

DEXRON-III Automatic Transmission Fluid.

Manual Transmission (Except ZF 6-Speed)

Synthetic Manual Transmission Fluid (GM Part No. U.S. 12345724, in Canada 10953510).

Manual Transmission (ZF 6-Speed)

TranSynd™ Synthetic Transmission Fluid (GM Part No. U.S. 12378515, in Canada 88900701).

Automatic Transmission

See the Allison Transmission Operator's Manual for correct transmission fluid.

Key Lock Cylinders

Multi-Purpose Lubricant, Superlube (GM Part No. U.S. 12346241, in Canada 10953474, or equivalent).

Chassis Lubrication

Chassis Lubricant (GM Part No. U.S. 12377985, in Canada 88901242, or equivalent) or lubricant meeting requirements of NLGI #2, Category LB or GC-LB.

Front Wheel Bearing Grease (Except Oil Filled Hubs)

Wheel bearing lubricant meeting requirements of NLGI #2, Category GC or GC--LB (GM Part No. U.S. 1051344, in Canada 993037, or equivalent).

Front Wheel Bearing Grease with Oil Filled Hubs

SAE 75W-90 Synthetic Axle Lubricant for Medium Duty Trucks (GM Part No. U.S. 12345841, in Canada 10953512, or equivalent).

Rear Axle and Rear Hubs

SAE 75W-90 Synthetic Axle Lubricant for Medium Duty Trucks (GM Part No. U.S. 12345841, in Canada 10953512, or equivalent).

Rear Axle Shift Motor Lubricant

Refrigerant Oil (GM Part No.U.S. 5416939, in Canada 10953496).

Propshafts and Splines

Wheel bearing lubricant meeting requirements of NLGI #2, Category GC or GC--LB (GM Part No. U.S. 1051344, in Canada 993037, or equivalent).

Cab -- Door Hinges and Latches

Multi-Purpose Lubricant, Superlube (GM Part No. U.S. 12346241, in Canada 10953474, or equivalent).

Weatherstrip Conditioning

Dielectric Silicone Grease (GM Part No. U.S. 12345579, in Canada 10953014, or equivalent).

Weatherstrip Squeaks

Synthetic Grease with Teflon, Superlube (GM Part No. U.S. 12371287, in Canada 10953437, or equivalent).