Ford Full-Size Vans 1989-1996 Repair Guide

Fuel and Engine Oil Recommendations




All 1987-96 Ford full size vans must use lead-free gasoline with a minimum octane rating of 87(as listed on the pumps), which usually means regular unleaded. Some areas may have 86 or even lower octane available, which would make 87 midgrade. In such cases, a minimum fuel octane of 87 should STILL be used.

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.

The use of a leaded fuel in a vehicle 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. Obviously, use of leaded fuel should not be a problem, since most companies have stopped selling it for quite some time.

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. The use of a fuel too low in octane (a measurement 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 different brand or 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 buildup, which will in turn change the compression ratio. If your engine pings or knocks, switch to a higher grade of fuel. Sometimes, just changing brands will cure the problem.

The other most important quality you should look for in a fuel is that it contains detergents designed to keep fuel injection systems clean. Many of the major fuel companies will display information right at the pumps telling you that their fuels contain these detergents. The use of a high-quality fuel which contains detergents will help assure trouble-free operation of your van's fuel system.

Engine Oil

See Figures 1 and 2

Click image to see an enlarged view

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

Click image to see an enlarged view

Fig. Fig. 2: Engine oil viscosities

The recommended oil viscosities for sustained temperatures ranging from below 0° (-18°C) to above 32°F (0°C) are listed in the section. They are broken down into multi-viscosities and single viscosities. Multi-viscosity oils are recommended because of their wider range of acceptable temperatures and driving conditions.

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

The Society of Automotive Engineers (SAE) grade number of the 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 viscosities 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 temperature 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 van 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 a heavier oil. But after the engine reaches operating temperature, the 10W-40 oil begins acting like straight 40-weight (SAE 40) oil. It behaves as a heavier oil, providing greater lubrication and protection against foaming than lighter oils.

The American Petroleum Institute (API) designations, also found on oil containers, indicate the classification of engine oil used for given operating conditions. Only oils designated Service SH (or the latest superseding designation) should be used in your van. Oils of the SH-type perform many 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, 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 never be used in your Ford gasoline engine.


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 oils, which can be three or four times the price per quart of conventional oil.

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

Depending on the type of synthetic oil, brand new engines and older, high mileage engines can be the wrong candidates for synthetic oil. In some cases, the synthetic oil is so slippery that it can prevent the proper break-in of new engines. With the exception of vehicles that are equipped with certain brands of synthetic oil from the factory, most manufacturers recommend that you wait until the engine is properly broken in (3,000 miles) before using synthetic oil. Older engines with wear have a different problem with some synthetics: they "use" (consume during operation) more oil as they age. Slippery synthetic oils get past these worn parts easily. If your engine is "using" conventional oil, it may use synthetics much faster. Also, if your van is leaking oil past old seals you'll have a much greater leak problem with synthetics.

Consider your type of driving, and consult someone knowledgeable on the particular brand of oil you are thinking of using. If most of your accumulated mileage is high speed, highway type driving, the more expensive synthetic oils may be a benefit. Extended highway driving gives the engine a chance to warm up, accumulating less acids in the oil and putting less stress on the engine over the long run. Under these conditions, the oil change interval can be extended (as long as your oil filter can last the extended life of the oil) up to the advertised mileage claims of the synthetics. Trucks with synthetic oils may show increased fuel economy in highway driving, due to less internal friction. However, many automotive experts agree that 50,000 miles (80,000 km) is too long to keep any oil in your engine.

Trucks used under harder circumstances, such as stop-and-go, city type driving, short trips, or extended idling, should be serviced more frequently. For the engines in these trucks, the much greater cost of synthetic or fuel-efficient oils may not be worth the investment. Internal wear increase much quicker on these trucks, causing greater oil consumption and leakage.

Read the label of the synthetic oil before you contemplate mixing it with conventional oils; not all synthetic and conventional oils are compatible. If you are using synthetic oil, it might be wise to carry two or three quarts with you no matter where you drive, as not all service stations carry this type of lubricant. Non-detergent or straight mineral oils must never be used.



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 its cetane number and its viscosity.

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 forming in the fuel. 20°F (-7°C) is often call 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 no start condition 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.

No. 1 and No. 2 diesel fuels will mix and burn with no ill effects, although the engine manufacturer recommends one or the other. Consult the owner's manual for information.

Depending on local climate, most fuel manufacturers make winterized No. 2 fuel available seasonally.

Many automobile manufacturers publish pamphlets giving the locations of diesel fuel stations nationwide. Contact the local dealer for information.

Do not substitute home heating oil for automotive diesel fuel. While in some cases, home heating oil refinement levels equal those of diesel fuel, many times they are far below diesel engine requirements. The result of using dirty home heating oil will be a clogged fuel system, in which case the entire system may have to be dismantled and cleaned.

One more word on diesel fuels. Don't thin diesel fuel with gasoline in cold weather. The lighter gasoline, which is more explosive, will cause rough running at the very least, and may cause extensive damage to the fuel system if enough is used.

Engine Oil

See Figure 2

Diesel engines require different engine oil from those used in gasoline engines. Besides doing the things gasoline engine oil does, diesel oil must also deal with increased engine heat and the diesel blow-by gases, which create sulfuric acid, a high corrosive.

Under the American Petroleum Institute (API) classifications, gasoline engine oil codes begin with an S , and diesel engine oil codes begin with a C . This first letter designation is followed by a second letter code which explains what type of service (heavy, moderate, light) the oil is meant for. For example, the label of a typical oil bottle will include: API SERVICES SH, CD. This means the oil in the bottle is a superior, heavy duty engine oil when used in a diesel engine.

Many diesel manufacturers recommend an oil with both gasoline and diesel engine API classifications.

Ford specifies the use of an engine oil conforming to API service categories of both SH and CD. DO NOT use oils labeled as only SH or only CD, as they could cause engine damage.


If you plan to drive your van 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.