GM Bonneville/Eighty Eight/LeSabre 1986-1999

Fuel and Engine Oil Recommendations

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FUEL RECOMMENDATIONS



Some fuel additives contain chemicals that can damage the catalytic converter and/or oxygen sensor. Read all of the labels carefully before using any additive in the engine or fuel system.

All of the vehicles covered by this information are designed to run on unleaded fuel. The use of a leaded fuel in a car requiring unleaded fuel will plug the catalytic converter and render it inoperative. It will also increase exhaust backpressure to the point where engine output will be severely reduced. The minimum octane rating of the unleaded fuel being used must be at least 87, which usually means regular unleaded, but some high performance engines may require higher ratings. Fuel should be selected for the brand and octane which performs best with your engine. Judge a gasoline by its ability to prevent pinging, its engine starting capabilities (cold and hot) and general all weather performance.

As far as the octane rating is concerned, refer to the general engine specifications chart in Engine & Engine Overhaul of this repair guide to find your engine and its compression ratio. If the compression ratio is 9.0:1 or lower, in most cases a regular unleaded grade of gasoline can be used. If the compression ratio is higher than 9.0:1 use a premium grade of unleaded fuel.

All of the engines covered by this information required a fuel with an octane rating of 87 or higher, except for the supercharged engine. The supercharged engine requires premium fuel with an octane rating of 92 or higher.

The use of a fuel too low in octane (a measure of anti-knock quality) will result in spark knock. Since many factors such as altitude, terrain, air temperature and humidity affect operating efficiency, knocking may result even though the recommended fuel is being used. If persistent knocking occurs, it may be necessary to switch to a higher grade of fuel. Continuous or heavy knocking may result in engine damage.

Your engine's fuel requirement can change with time, mainly due to carbon build-up, which will in turn change the compression ratio. If you engine pings, knocks or diesels (runs with the ignition OFF) switch to a higher grade of fuel. Sometimes, just changing brands will cure the problem. If it becomes necessary to retard the timing from the specifications, don't change it more than a few degrees. Retarded timing will reduce power output and fuel mileage, in addition to making the engine run hotter.

OIL RECOMMENDATIONS



See Figures 1 and 2

The Society Of Automotive Engineer (SAE) grade number indicates the viscosity of the engine oil and thus its ability to lubricate at a given temperature. The lower the SAE grade number, the lighter the oil; the lower the viscosity, the easier it is to crank the engine in cold weather. Oil viscosities should be chosen from those oils recommended for the lowest anticipated temperatures during the oil change interval. With the proper viscosity, you will be assured of easy cold starting and sufficient engine protection.



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Fig. Fig. 1: Look for the API oil identification label when choosing your engine oil

Multi-viscosity oils (5W-30, 10W-30 etc.) offer the important advantage of being adaptable to temperature extremes. They allow easy starting at low temperatures, yet they give good protection at high speeds and engine temperatures. This is a decided advantage in changeable climates or in long distance driving.



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Fig. Fig. 2: Recommended SAE engine oil viscosity grades for gasoline engines

The American Petroleum Institute (API) designation indicates the classification of engine oil used under certain given operating conditions. Only oil designated for Service SJ, or latest superseding oil grade, should be used. Oils of the SJ type perform a variety of functions inside the engine in addition to their basic function as a lubricant. Through a balanced system of metallic detergents and polymeric dispersants, the oil prevents the formation of high and low temperature deposits and also keeps sludge and particles of dirt in suspension. Acids, particularly sulfuric acid, as well as other byproducts of combustion, are neutralized. Both the SAE grade number and the API designation can be found on the side of the oil bottle.

Synthetic Oils

There are excellent synthetic and fuel-efficient oils available that, under the right circumstances, can help provide better fuel mileage and better engine protection. However, these advantages come at a price, which can be significantly more than the price per quart of conventional motor oils.

Before pouring any synthetic oils into your car's engine, you should consider the condition of the engine and the type of driving you do. It is also wise to check the vehicle manufacturer's position on synthetic oils.

Generally, it is best to avoid the use of synthetic oil in both brand new and older, high mileage engines. New engines require a proper break-in, and the synthetics are so slippery that they can impede this; most manufacturers recommend that you wait at least 5,000 miles (8,000 km) before switching to a synthetic oil. Conversely, older engines are looser and tend to lose more oil; synthetics will slip past worn parts more readily than regular oil. If your car already leaks oil, (due to worn parts or bad seals/gaskets), it may leak more with a synthetic inside.

Consider your type of driving. If most of your accumulated mileage is on the highway at higher, steadier speed, a synthetic oil will reduce friction and probably help deliver better fuel mileage. Under such ideal highway conditions, the oil change interval can be extended, as long as the oil filter can operated effectively for the extended life of the oil. If the filter can't do its job for this extended period, dirt and sludge will build up in your engine's crankcase, sump, oil pump and lines, no matter what type of oil is used. If using synthetic oil in this manner, your should continue to change the oil filter at the recommended intervals.

Cars used under harder, stop-and-go, short hop circumstances should always be serviced more frequently, and for these cars synthetic oil may not be a wise investment. Because of the necessary shorter change interval needed for this type of driving, you cannot take advantage of the long recommended change interval of most synthetic oils.

OIL LEVEL CHECK



See Figures 3 and 4

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. Because it takes some time for 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 car is parked on level ground.
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  3. When checking the oil level, it is best for the engine to be at 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. Pull the dipstick from its tube, wipe it clean (using a clean, lint free rag) and then reinsert it, making sure that you push it back in completely.
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Fig. Fig. 3: Locate the engine oil dipstick, which should be found at the front of the engine, and pull it out of the tube

  1. Pull the dipstick back out, hold it horizontally, and check the level at the end of the dipstick. Some dipsticks are marked with ADD and FULL lines, others with ADD 1 QT and OPERATING RANGE , or crosshatched area. In either case, the level must be above the ADD line. Reinsert the dipstick completely.
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Fig. Fig. 4: The oil level should be within the crosshatched area on the dipstick (between the photo's arrows)

  1. If oil must be added, it can be poured in through the rocker (valve) cover after removing the filler cap on the cover. 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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  3. Insert 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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WARNING
DO NOT overfill the crankcase. It may result in oil-fouled spark plugs, oil leaks cause by oil seal failure or engine damage due to oil foaming.

  1. Be sure that the dipstick and oil filler cap are installed before closing the hood.
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OIL & FILTER CHANGE



See Figures 5 through 14

On these vehicles, you need a 14mm wrench or socket to loosen the oil pan drain plug.

The manufacturer's recommended oil change interval is 7500 miles (12,000 km) under normal operating conditions. We recommend an oil change interval of 3000-3500 miles (4800-5600 km) under normal conditions; more frequently under severe conditions such as when the average trip is less than 4 miles (6 km), the engine is operated for extended periods at idle or low-speed, when towing a trailer or operating in dusty areas.

Always replace the oil filter every time you change the oil. 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.

  1. Drive the car until the engine is at normal operating temperature. A run to the parts store for oil and a filter should accomplish this. If the engine is not hot when the oil is changed, most of the acids and contaminants will remain inside the engine.
  2.  

Please be considerate of the environment. Dispose of waste oil properly by taking it to a service station, municipal facility or recycling center.

  1. Run the engine until it reaches normal operating temperature. The turn the engine OFF .
  2.  
  3. Raise and safely support the front of the vehicle using jackstands.
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  5. Slide a pan of at least six quarts capacity under the oil pan. Wipe the drain plug and surrounding area clean using an old rag.
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  7. Loosen the drain plug using a ratchet, short extension and socket, or a box-wrench. The drain plug is the bolt inserted at an angle into the lowest point of the oil pan. 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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Fig. Fig. 5: Use a box end wrench to break the oil pan drain plug loose



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Fig. Fig. 6: Keeping inward pressure when unthreading the drain plug helps avoid spilling hot oil all over your hand



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Fig. Fig. 7: Quickly withdraw the plug from the oil pan, and allow the oil to drain completely



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Fig. Fig. 8: Clean off and inspect the oil pan drain plug (1) and washer (2), and replace if necessary



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Fig. Fig. 9: Use an oil filter wrench or adapter with a ratchet (shown) to loosen the oil filter



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Fig. Fig. 10: Remember, the oil filter holds about a quart of dirty oil that will probably drip out as the filter is loosened ...



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Fig. Fig. 11: ... so you may want to wear protective gloves when removing the filter



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Fig. Fig. 12: Clean the oil filter mounting boss with a clean, lint-free rag before installing a new filter

  1. 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, then reinstall the drain plug. Do not overtighten the plug.
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  3. Wipe off the drain plug, removing any traces of metal particles. Check the condition of the plastic drain plug gasket. If it is cracked or distorted in any way, replace it. Reinstall the drain plug and gasket. Tighten the drain plug snugly.
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The oil filter is just about impossible to reach from above, and almost as inaccessible from below. It may be easiest to remove the front wheel to allow more room to work on some models.

  1. Place the drain pan on the ground, under the filter. Use a strap or cap type wrench to loosen the oil filter; these are available at auto parts stores. Unscrew and discard the old filter. It will be VERY HOT, so be careful.
  2.  

Regardless of which type wrench you decide to use, be sure to obtain the correct size; filter wrenches come in different sizes (as do oil filters), and one size does not fit all.

  1. If the oil filter is on so tightly that it collapses under pressure from the wrench, move the wrench as close to the engine as possible. If the filter hasn't torn, but can't turn, it may be to your advantage to take it to a shop before a leak develops. It is next to impossible to cut these filters off without special tools. Make sure you are turning it counterclockwise.
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  3. Clean off the oil filter mounting surface with a rag. Apply a thin film of clean engine oil to the filter gasket.
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Fig. Fig. 13: Before installing a new oil filter, lightly coat the rubber gasket with clean oil

  1. Screw the filter on by hand until the gasket makes contact. Then tighten it by hand an additional 1 / 2 to 3 / 4 of a turn. Do not overtighten.
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  3. If raised, carefully lower the vehicle.
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  5. Refill the crankcase with the correct amount of fresh engine oil. Please refer to the Capacities chart in this section.
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Fig. Fig. 14: Using a funnel when adding engine oil to the crankcase will prevent making a mess

  1. Check the oil level on the dipstick. It is normal or 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 is to pour it into plastic jugs, such as milk or old antifreeze containers. Then, locate a service station or automotive parts store where you can pour it into their used oil tank for recycling.

Improperly disposing of used motor oil not only pollutes the environment, it violates Federal law. Dispose of waste oil properly.

 
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