Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Hello Big Red,
Many engines today do not use a PCV system however all perform the same function. What a PCV system does is pull crankcase vapors through the valve into the intake manifold to burn them. Your system uses a very precisely measured orifice tube which serves the same function. It will not cause it to burn more or less oil than the PCV valve equipped system. So as you can see both pull vapors into the manifold just in a different way. Now for the consumption of your oil. It sounds like you have been informed somewhat that this amount of oil is considered normal by GM and that is accurate. Here is their consumption chart to determine if there is a problem and you will see their suggestions. It is fairly common to experience this but is vehicle dependant, meaning another of the exact model may be different. Also with that consumption level it will likely do no harm to the converters.
nfo - Higher Than Expected Oil Consumption (Greater Than 8500 GVW) #03-06-01-023 - (08/19/2003)
2000-2004 Chevrolet Express, Silverado, Suburban
2002-2004 Chevrolet Avalanche
2000-2004 GMC Savana, Sierra, Yukon XL
2003-2004 Chevrolet Kodiak C4500-C5500 Series Models
2003-2004 GMC Topkick C4500-C5500 Series Models
2003-2004 HUMMER H2
with Gasoline Engines and Rated at 8600 GVW and above
Information on Engine Oil Consumption Guidelines
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 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 for vehicles at or above 8600 GVW.
The accepted rate of oil consumption for gasoline engines in vehicles at or above 8600 GVW 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 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.
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 at highway speeds, and thus increases the rate of oil consumption.
Operation of a PTO will increase fuel and oil usage, as the PTO driven accessory uses engine power to operate.
Crankcase Ventilation System
Verify that the positive crankcase ventilation (PCV) system is operating properly. Blockages, restrictions or damage to the PCV system can result in increased oil use.
Oil Dilution from Condensation
On vehicles that are usually driven short distances, less than 8 km (5 mi), especially in colder weather, condensation generated from cold engine operation may not get hot enough to evaporate out of the oil. When this occurs, the dipstick may indicate that the oil level is over-full. Subsequent driving on a trip of sufficient length to enable normal engine operating temperature for 30 minutes or more, in order to vaporize excess moisture, may give the customer the impression of excessive oil consumption.
If an engine is run at overheated temperatures (see Owner's Manual or Service Manual) for more than brief periods, oil will oxidize at a faster than normal rate. In addition, gaskets may distort, piston rings may stick, and excessive wear may result. Verify that all cooling system components are in proper working order.
Piston scuffing, excessive piston-to-wall clearance, tapered or out of round cylinders, worn, damaged or improperly installed valve guides, seals and piston rings will all cause an increase in oil consumption.
Measurement of Oil Consumption
Engines require a period of time to BREAK IN so that moving parts are properly seated. Therefore, oil economy should not be tested until the vehicle has accumulated at least 8000 km (5000 mi) and the oil has been changed for the first time. During initial engine break-in periods before the first oil change, oil consumption may exceed 1.9 liters (2 quarts) or more per 379 liters (100 gallons) of fuel used.
Oil Consumption Worksheet
TAC Case #
FUEL QUANTITY ADDED
OIL QUANTITY ADDED
Qt/Gal or L/L
Oil consumption of 0.946L/379L of fuel (1 qt./100 gal.) or less is considered acceptable.
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Document ID#(NNN) NNN-NNNN2002 Chevrolet Chevy C Silverado - 2WD
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