GM S-Series Pick-ups and SUV's 1994-1999 Repair Guide

Engine

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OIL LEVEL CHECK



See Figures 1, 2, 3, and 4



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Fig. Fig. 1: Remove the dipstick from the tube, wipe it clean, then reinsert it



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Fig. Fig. 2: Remove the dipstick again and, while holding it horizontally, read the oil level



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Fig. Fig. 3: If oil needs to be added, remove the oil filler cap ...



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Fig. Fig. 4: ... then using a funnel to avoid spillage, add the correct amount and grade of oil

Every time you stop for fuel, check the engine oil making sure the engine has fully warmed and the vehicle is parked on a level surface. If the truck is used for trailer towing or for heavy-duty use, it is recommended to check the oil more frequently. Because it takes a few minutes for all the oil to drain back to the oil pan, you should wait a few minutes before checking your oil. If you are doing this at a fuel stop, first fill the fuel tank, then open the hood and check the oil, but don't get so carried away as to forget to pay for the fuel. Most station attendants won't believe that you forgot.

  1. Make sure the truck is parked on level ground.
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  3. When checking the oil level it is best for the engine to be a normal operating temperature, although checking the oil immediately after stopping will lead to a false reading. Wait a few minutes after turning off the engine to allow the oil to drain back into the crankcase.
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  5. Open the hood and locate the dipstick which will be in a guide tube mounted in the upper engine block, just below the cylinder head mating surface. The dipstick may be located on the right or left side of the vehicle depending upon your particular engine. Pull the dipstick from its tube, wipe it clean (using a clean, lint free rag) and then reinsert it.
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  7. Pull the dipstick out again and, holding it horizontally, read the oil level. The oil should be between the FULL and ADD marks on the dipstick. If the oil is below the ADD mark, add oil of the proper viscosity through the capped opening in the top of the cylinder head cover or filler tube, as applicable. See the oil and fuel recommendations listed earlier in this section for the proper viscosity and rating of oil to use.
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  9. Replace the dipstick and check the oil level again after adding any oil. Approximately one quart of oil will raise the level from the ADD mark to the FULL mark. Be sure not to overfill the crankcase and waste the oil. Excess oil will generally be consumed at an accelerated rate.
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OIL AND FILTER CHANGE



See Figures 5 through 11



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Fig. Fig. 5: Remove the oil pan drain plug and drain all the oil from the crankcase



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Fig. Fig. 6: On some early model 4.3L engines the oil filter is located behind an access panel. If this is the case, open the oil filter access panel located at the front of the vehicle



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Fig. Fig. 7: Using the proper size oil filter wrench, remove the old oil filter



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Fig. Fig. 8: Before installing a new oil filter, lightly coat the rubber gasket with clean oil



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Fig. Fig. 9: Add the proper amount and grade of engine oil to the engine



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Fig. Fig. 10: After adding the oil, check the dipstick to ensure that the crankcase is filled to the proper level



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Fig. Fig. 11: Remember to always replace the engine oil filler cap after adding oil

If the vehicle is operated on a daily or semi-daily basis and most trips are for several miles (allowing the engine to properly warm-up), the oil should be changed a minimum of every 12 months or 7500 miles (12,000 Km), whichever comes first.

If however, the vehicle is used to tow a trailer, is made to idle for extended periods of time such as in heavy daily traffic or if used as a service vehicle (delivery) or the vehicle is used for only short trips in below freezing temperature, the oil change interval should be shortened. Likewise, if your vehicle is used under dusty, polluted or off-road conditions, the oil should be changed more frequently. Under these circumstances oil has a greater chance of building up sludge and contaminants which could damage your engine. If your vehicle use fits into these circumstance, as most do, it is suggested that the oil and filter be changed every 3000 miles (4800 Km) or 3 months, whichever comes first.

Under certain circumstances, Chevrolet and GMC recommend changing both the oil and filter during the first oil change and then only replacing the filter every other oil change thereafter. For the small price of an oil filter, it's cheap insurance to replace the filter at every oil change. One of the larger filter manufacturers points out in its advertisements that not changing the filter leaves one quart of dirty oil in the engine. This claim is true and should be kept in mind when changing your oil.

Oil should always be changed after the engine has been running long enough to bring it up to normal operating temperature. Hot oil will flow easier and more contaminants will be removed along with the oil than if it were drained cold. The oil drain plug is located on the bottom of the oil pan (bottom of the engine, underneath the vehicle). The oil filter is usually located on the left side of the engine and in some cases may be easier to reach through the plastic access flap in the wheel well. On some older 4.3L models, the oil filter is located behind a access panel.

You should have available a container that will hold a minimum of 6 quarts (5.6L) of liquid (to help prevent spilling the oil even after it is drained), a wrench to fit the drain plug, a spout for pouring in new oil and a rag or two, which you will always need. If the filter is being replaced, you will also need a band wrench or a filter wrench that fits the end of the filter.

If the engine is equipped with an oil cooler, this will also have to be drained, using the drain plug. Be sure to add enough oil to fill the cooler in addition to the engine.

  1. Run the engine until it reaches normal operating temperature, then shut the engine OFF , make sure the parking brake is firmly set and block the drive wheels.
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  3. Clearance may be sufficient to access the drain plug without raising the vehicle. If the truck must be lifted, be sure to support it safely with jackstands and be sure to position the drain plug at a low point under the vehicle.
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  5. Slide a drain pan of a least 6 quarts (5.6L) capacity under the oil pan. Wipe the drain plug and surrounding area clean using an old rag.
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CAUTION
The EPA warns that prolonged contact with used engine oil may cause a number of skin disorders, including cancer! You should make every effort to minimize your exposure to used engine oil. Protective gloves should be worn when changing the oil. Wash your hands and any other exposed skin areas as soon as possible after exposure to used engine oil. Soap and water, or waterless hand cleaner should be used.

  1. Loosen the drain plug (the plug is usually about 15mm) using a ratchet, short extension and socket or a box-wrench. Turn the plug out by hand, using a rag to shield your fingers from the hot oil. By keeping an inward pressure on the plug as you unscrew it, oil won't escape past the threads and you can remove it without being burned by hot oil.
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  3. Quickly withdraw the plug and move your hands out of the way, but be careful not to drop the plug into the drain pan as fishing it out can be an unpleasant mess. Allow the oil to drain completely in the pan, then install and carefully tighten the drain plug. Be careful not to overtighten the drain plug, otherwise you'll be buying a new pan or a trick replacement plug for stripped threads.
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Although some manufacturers have at times recommended changing the oil filter every other oil change, we recommend the filter be changed each time you change your oil. The added benefit of clean oil is quickly lost if the old filter is clogged and the added protection to the heart of your engine far outweighs the few dollars saved by using a old filter.

  1. Move the drain pan under the oil filter. Use a strap-type or cap-type filter wrench to loosen the oil filter. Cover your hand with a rag and spin the filter off by hand; turn it slowly. Keep in mind that it's holding about one quart of dirty, hot oil.
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CAUTION
On most Chevrolet engines, especially the V6s, the oil filter is next to the exhaust pipes. Stay clear of these, since even a passing contact can result in a painful burn. ALSO, on trucks equipped with catalytic converters, stay clear of the converter. The outside temperature of a hot catalytic converter can approach 1200ºF.

  1. Empty the old filter into the drain pan and properly dispose of the filter.
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  3. Using a clean rag, wipe off the filter adapter on the engine block. Be sure that the rag doesn't leave any lint which could clog an oil passage.
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  5. Coat the rubber gasket on the filter with fresh oil, then spin it onto the engine by hand; when the gasket touches the adapter surface, give it another 1 / 2 -1 turn. No more, or you'll squash the gasket and it will leak.
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  7. Refill the engine with the correct amount of fresh oil. Please refer to the Capacities chart at the end of this section.
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  9. Check the oil level on the dipstick. It is normal for the level to be a bit above the full mark until the engine is run and the new filter is filled with oil. Start the engine and allow it to idle for a few minutes.
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CAUTION
Do not run the engine above idle speed until it has built up oil pressure, as indicated when the oil light goes out.

  1. Shut off the engine and allow the oil to flow back to the crankcase for a minute, then recheck the oil level. Check around the filter and drain plug for any leaks, and correct as necessary.
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When you have finished this job, you will notice that you now possess four or five quarts of dirty oil. The best thing to do with it is to pour it into plastic jugs, such as milk or antifreeze containers. Then, locate a service station or automotive parts store where you can pour it into their used oil tank for recycling.


CAUTION
Pouring used motor oil into a storm drain not only pollutes the environment, it violates Federal law. Dispose of waste oil properly.

 
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