Diesel Engine - Higher Than Expected Oil

File In Section: 06 - Engine/Propulsion System

Bulletin No.: 02-06-01-027

Date: August, 2002

INFORMATION
Subject:
Higher Than Expected Oil Consumption

Models:
2001-2003 Chevrolet Silverado 2500-3500 Series Models
2001-2003 GMC Sierra 2500-3500 Series Models
2003 Chevrolet Kodiak C4500-C5500 Series Models
2003 GMC Topkick C4500-C5500 Series Models with 6.6L Duramax(TM) Diesel Engine (VIN 1 - RPO LB1)

Information on Engine Oil Consumption Guidelines for the 6.6L Duramax Diesel Engine

All engines require oil to lubricate and protect the load bearing and internal moving parts from wear including cylinder walls, pistons and piston rings. When a piston moves down its cylinder, a thin film of oil is left on the cylinder wall. During the combustion process, part of this oil layer is consumed. As a result, varying rates of oil consumption are accepted as normal in all engines.

Oil Consumption

Oil usage has a direct relationship with the amount of fuel used. The harder an engine works, the more fuel and oil it will use. Therefore, oil usage as a factor of fuel usage is a more accurate indicator of acceptable oil consumption levels than vehicle mileage.

The accepted rate of oil consumption for the 6.6L Duramax(TM) Diesel engine is 0.946 liter (1 qt) within 379 liters (100 gallons) of fuel used. This rate only applies to vehicles under warranty, maintained in accordance with the appropriate maintenance schedule, driven at legal speeds and within design intent of the vehicle.

Many factors can affect an owner's concern with oil consumption. Driving habits and vehicle maintenance vary from owner to owner. Thoroughly evaluate each case before deciding whether the vehicle in question has abnormal engine oil consumption.

Gasket and External Leaks

Inspect the oil pans, engine covers, and the engine oil cooler for leakage. Inspect the turbocharger oil lines and fittings for signs of leakage. Inspect the turbocharger outlet pipe for signs of oil, indicating worn turbocharger shaft bushings or seals. Inspect for oil leakage into the engine coolant.

Improper Reading of the Oil Level Indicator (Dipstick)

The vehicle must be parked on a level surface to obtain accurate oil level readings. Verify that the dipstick tube is fully seated in the block. When checking the oil level, make sure the dipstick is wiped clean before taking an oil level reading and fully depress the dipstick until the shoulder bottoms out on the dipstick tube. The dipstick should be the proper part number for the engine/vehicle that is being checked.

Not Waiting Long Enough After Running Engine to Check Oil Level

The vehicle should be allowed to sit for at least 15 minutes, after the engine has been shut off, before taking an oil level reading to assure the oil has had enough time to drain back into the crankcase. In order to ensure accurate results, the temperature of the oil should be close to the same temperature as the last time the oil level was checked.

Improper Oil Fill After an Oil Change

Following an oil change, verify that the proper amount and type of oil was put in the engine and that the oil level on the dipstick is not above the full mark or below the add marks. Refer to the Owner's Manual or Service Manual for information on recommended oil quantity, viscosity, and quality. Diesel engines require a CH-4 or CG-4 oil rating.

High Speed or High RPM Driving

Continuous driving at high speeds/high RPMs may increase oil consumption. Because this may not always be an everyday occurrence, it is hard to determine exactly how much the oil economy will be affected.

Towing or Heavy Usage

Towing a trailer or hauling additional weight will increase oil consumption. Large frontal area trailers will further increase the work required from the engine, especially