Engine Oil

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. GM Goodwrench oil meets all the requirements for your vehicle. To determine the preferred viscosity for your vehicle's diesel engine, see Engine Oil .

Engine Coolant

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

Washer Solvent (Part No. 2-90531-811-0).

Clutch Bearing Lubricant

Clutch Bearing Lubricant (NLGI #3 consistency).

Exhaust Brake Ball Joint Cap Lubricant

High-Temperature Grease (NLGI #3 consistency).

Power Steering System

DEXRON-III Automatic Transmission Fluid.

Manual Transmission

Synthetic Manual Transmission Fluid.

Automatic Transmission

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

Key Lock Cylinders

Multi-Purpose Lubricant, Superlube (Part No. 2-90531-804-0).

Chassis Lubrication

Chassis 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.

Front Wheel Bearing Grease with Oil Filled Hubs

SAE 75W-90 Synthetic Axle Lubricant for Medium Duty Trucks.

Rear Axle and Rear Hubs

SAE 75W-90 Synthetic Axle Lubricant for Medium Duty Trucks.

Rear Axle Shift Motor Lubricant

Refrigerant Oil.

Propshafts and Splines

Wheel bearing lubricant meeting requirements of NLGI #2, Category GC or GC-LB.

Cab -- Door Hinges and Latches

Multi-Purpose Lubricant, Superlube (Part No. 2-90531-804-0).

Weatherstrip Conditioning

Dielectric Silicone Grease.

Weatherstrip Squeaks

Synthetic Grease with Teflon, Superlube.