Mitsubishi Galant/Mirage/Diamante 1990-2000

Fuel and Engine Oil Recommendations



Mitsubishi recommends that SAE 5W-30 viscosity engine oil should be used for all climate conditions, however, SAE 10W-30 is acceptable for vehicles operated in moderate-to-hot climates.

When adding oil to the crankcase or changing the oil or filter, it is important that oil of an equal quality to original equipment be used in your car. The use of inferior oils may void the warranty, damage your engine, or both.

The SAE (Society of Automotive Engineers) grade number of oil indicates the viscosity of the oil (its ability to lubricate at a given temperature). The lower the SAE number, the lighter the oil; the lower the viscosity, the easier it is to crank the engine in cold weather but the less the oil will lubricate and protect the engine in high temperatures. This number is marked on every oil container.

Oil viscosity's should be chosen from those oils recommended for the lowest anticipated temperatures during the oil change interval. Due to the need for an oil that embodies both good lubrication at high temperatures and easy cranking in cold weather, multigrade oils have been developed. Basically, a multigrade oil is thinner at low temperatures and thicker at high temperatures. For example, a 10W-40 oil (the W stands for winter) exhibits the characteristics of a 10 weight (SAE 10) oil when the car is first started and the oil is cold. Its lighter weight allows it to travel to the lubricating surfaces quicker and offer less resistance to starter motor cranking than, say, a straight 30 weight (SAE 30) oil. But after the engine reaches operating temperature, the 10W-40 oil begins acting like straight 40 weight (SAE 40) oil, its heavier weight providing greater lubrication with less chance of foaming than a straight 30 weight oil.

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

The API (American Petroleum Institute) designations, also found on the oil container, indicates the classification of engine oil used under certain given operating conditions. Only oils designated for use Service SJ, or latest superceding designation, heavy duty detergent should be used in your car. Oils of the SJ type perform may functions inside the engine besides their basic lubrication. Through a balanced system of metallic detergents and polymeric dispersants, the oil prevents high and low temperature deposits and also keeps sludge and dirt particles in suspension. Acids, particularly sulfuric acid, as well as other by-products of engine combustion are neutralized by the oil. If these acids are allowed to concentrate, they can cause corrosion and rapid wear of the internal engine parts.

Non-detergent motor oils or straight mineral oils should not be used in your engine.

Synthetic Oil

There are many excellent synthetic and fuel-efficient oils currently available that can provide better gas mileage, longer service life and, in some cases, better engine protection. These benefits do not come without a few hitches, however; the main one being the price of synthetic oil, which is significantly more expensive than conventional oil.

Synthetic oil is not for every car and every type of driving, so you should consider your engine's condition and your type of driving. Also, check your car's warranty conditions regarding the use of synthetic oils.


All models equipped with a SOHC (Single Overhead Camshaft) engine are designed to operate using regular unleaded fuel with a minimum of 87 octane. All models equipped with a DOHC (Dual Overhead Camshaft) engine are designed to operate using regular unleaded fuel with a minimum of 91 octane. Mitsubishi warns that using gasoline with a lower octane rating can cause persistent and heavy knocking, and may cause internal engine damage.

If your vehicle is having problems with rough idle or hesitation when the engine is cold, it may be caused by low volatility fuel. If this occurs, try a different grade or brand of fuel.


If you plan to drive your car outside the United States or Canada, there is a possibility that fuels will be too low in anti-knock quality and could produce engine damage. It is wise to consult with local authorities upon arrival in a foreign country to determine the best fuels available.