Ford Tempo/Topaz 1984-1994 Repair Guide

Fuel and Engine Oil Recommendations


See Figures 1 and 2

It is important to use fuel of the proper octane rating in your vehicle. Octane rating is based on the anti-knock property of the fuel, and determines the speed at which it burns. The fuel recommended for your vehicle is "Unleaded Gasoline having a Research Octane Number (RON) of 91, or an Antiknock Index of 87. Do not get these number confused, because it can have an adverse effect on your engine. Remember, the number that is posted on most gasoline pumps is the antiknock index.

Using a high quality unleaded gasoline will help maintain the driveability, fuel economy and emissions performance of your vehicle. A properly formulated gasoline will be comprised of well refined hydrocarbons and chemical additives and will accomplish the following.

Minimize varnish, lacquer and other induction system deposits.
Prevent gum formation or other deterioration.
Protect the fuel tank and other fuel system components from corrosion or degradation.
Provide the correct seasonally and geographically adjusted volatility. This will provide easy starting in the winter and avoid vapor lock in the summer. Avoid fuel system icing.

In addition, the fuel will be free of water deposits and other impurities. Some driveability deterioration on multi-port electronically fuel injected vehicles can be traced to continuous use of certain gasoline which may have insufficient amounts of detergent additives to provide adequate deposit control protection. Many manufacturers recommend using two or three different blend gasoline at regular intervals.

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Fig. Fig. 1: Look for this oil identification label when purchasing oil for your vehicle

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Fig. Fig. 2: Engine oil viscosity recommendation


Fuel makers produce two grades of diesel fuel, No. 1 and No. 2, for use in automotive diesel engines. Generally speaking, No. 2 fuel is recommended over No. 1 for driving in temperatures above 20°F (-7°C). In fact, in many areas, No. 2 diesel is the only fuel available. By comparison, No. 2 diesel fuel is less volatile than No. 1 fuel, and gives better fuel economy. No. 2 fuel is also a better injection pump lubricant.

Two important characteristics of diesel fuel are the cetane number, and the viscosity rate. The cetane number of a diesel fuel refers to the ease with which a diesel fuel ignites. High cetane numbers mean that the fuel will ignite with relative ease or that it ignites well at low temperatures. Naturally, the lower the cetane number, the higher the temperature must be to ignite the fuel. Most commercial fuels have cetane numbers that range from 35 to 65. No. 1 diesel fuel generally has a higher cetane rating than No. 2 fuel.

Viscosity is the ability of a liquid, in this case diesel fuel, to flow. Using straight No. 2 diesel fuel below 20°F (-7°C) can cause problems, because this fuel tends to become cloudy, meaning wax crystals begin to form in the fuel. 20°F (-7°C) is often called the cloud point for No. 2 fuel. In extremely cold weather, No. 2 fuel can stop flowing altogether. In either case, fuel flow is restricted, which can result in a poor starting conditions or poor engine performance. Fuel manufacturers often winterize No. 2 diesel fuel by using various fuel additives and blends (no. 1 diesel fuel, kerosene, etc.) to lower its winter time viscosity. Generally speaking, though, No. 1 diesel fuel is more satisfactory in extremely cold weather.

The 2.0L diesel engine in the Tempo/Topaz is designed to use number 2-D diesel fuel. Use of number 1-D diesel fuel in temperatures +20°F(-7°C) is acceptable, but not necessary.

Do not use number 1-D diesel fuel in temperatures above +20°F (-7°C) as damage to the engine may result. Also fuel economy will be reduced with the use of number 1-D diesel fuel.

The 2.0L diesel engines are equipped with an electric fuel heater to prevent cold fuel problems. For best results in cold weather use winterized number 2-D diesel fuel which is blended to minimize cold weather operation problems.

DO NOT add gasoline, gasohol, alcohol or cetane improvers to the diesel fuel. Also, DO NOT use fluids such as ether (starting fluid) in the diesel air intake system. The use of these liquids or fluids will cause damage to the engine and/or fuel system.