Lubrication Types for a Chevy Diesel 6.5

by Jen Davis

There are a number of different fluids that are used in a General Motors or Chevrolet 6.5-liter diesel engine to keep it running smoothly and operating properly. Without the proper fluids, the truck's engine can be damaged by heat and friction that are generated as the engine runs. It is important to use the proper fluids in your diesel truck and keep the right amount of fluids in the engine at all times.


Engine oil is required for all gasoline and diesel engines. Oil provides the lubrication necessary to minimize friction between internal components. The 2011 Chevrolet Diesel Truck owner's manual insert states that Chevrolet diesel engines need to use engine oil that is designated as API CJ-4 and has a viscosity of SAE 15W-40, unless you are in extremely cold temperatures, where SAE 5W-40 can be used to improve cold starting. Chevrolet states that you should not use 10W-30, 10W-40 or 20W-50 oils in your 6.5 diesel engine. Oil should be changed every 3,000 miles.

Oil Flushes and Additives

Chevrolet states that vehicle owners should not add any kind of additional fluid to the recommended engine oil of their diesel trucks. Chevrolet does not recommend using oil additives or engine oil system flushes. These treatments may void your vehicle's warranty and cause damage.


The 6.5-liter diesel should operate using a 50/50 mixture of DEX-COOL coolant and clean, drinking-quality water in the radiator and cooling system. The coolant's purpose in the engine is to prevent overheating and extreme engine temperatures.

Other Fluids

Your 6.5-liter diesel engine and its various components rely on a number of different fluids to continue operating properly. These include DEXRON-VI automatic transmission fluid for the transmission and transfer case, GM-brand power steering and diesel exhaust fluid, and DOT-3 hydraulic brake fluid.

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