Honda Civic/CRX/del Sol 1984-1995 Repair Guide

Fuel and Engine Oil Recommendations



All Honda vehicles covered in this information are designed to run on unleaded fuel only.

You should be careful to use quality fuels having an octane rating of at least 86 when measured by the R/M method, which is an average of the "Research" and "Motor" octane ratings. Too low an octane rating may produce combustion knock, which may prove to be damaging to the engine. Always buy fuel from a reputable dealer, preferably where a regular volume is pumped so that the fuel is always fresh.


See Figure 1

Motor oil is often called the "life blood" of an engine. It is primarily responsible for lubricating the dozens of fast-moving, precision metal parts that make up an internal combustion engine. A sufficient supply of clean, high-quality oil is probably the single greatest factor in the longevity of any given engine. If the level dips too low, or the oil is old and becomes "broken down" (in molecular composition), severely accelerated wear and even sudden catastrophic engine failure could be the result. It pays to check your oil often and to change it on time.

The Society of Automotive Engineers (SAE) grade number indicates the viscosity of the engine oil (it's resistance to flow at a given temperature). The lower the SAE grade number, the lighter the oil. For example, the mono-grade oils begin with SAE 5 weight, which is a thin, light oil, and continue in viscosity up to SAE 80 or 90 weight, which are heavy gear lubricants. These oils are also known as "straight weight", meaning they are of a single viscosity, and do not vary with engine temperature.

Multi-viscosity oils offer the important advantage of being adaptable to temperature extremes. These oils have designations such as 10W-40, 20W-50, etc. For example, 10W-40 means that in winter (the "W" in the designation) the oil acts like a thin, 10 weight oil, allowing the engine to spin easily when cold and offering rapid lubrication. Once the engine has warmed up, however, the oil acts like a straight 40 weight, maintaining good lubrication and protection for the engine's internal components. A 20W-50 oil would therefore be slightly heavier and not as ideal in cold weather as the 10W-40, but would offer better protection at higher rpm and temperatures because, when warm, it acts like a 50 weight oil. Whichever oil viscosity you choose when changing the oil, make sure you are anticipating the temperatures your engine will be operating in until the oil is changed again. Refer to the oil viscosity chart for oil recommendations according to temperature.

Honda does not recommend the use of any oil additive or supplement in the engine. A normal engine does not need them. If the engine is worn or damaged, it's usually too late for any benefit.

The American Petroleum Institute (API) designation indicates the classification of engine oil used under certain operating conditions. Only oils designated for use "Service SG or SH" should be used. Oils of the SG/SH type perform a variety of functions inside the engine in addition to the basic function of lubrication. An SG/SH rated oil may be substituted for SF or SE oils in older vehicles. A new vehicle requiring SG/SH oil may be damaged by using oil with a lesser rating. API labels may also carry other letter ratings such as CD or CC; these oils are acceptable for use as long as the designation SG/SH is also present.

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 by-products of combustion, are neutralized. Both the SAE grade number and the API designation can be found on the label of the oil bottle. For recommended oil viscosities, refer to the chart.

Click image to see an enlarged view

Fig. Fig. 1: Oil viscosity chart

Synthetic Oil

There are many excellent synthetic 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 drawback is the price of synthetic oils, which is three or four times the price per quart of conventional oil.

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

Both brand new engines and older, high mileage engines are the wrong candidates for synthetic oil. The synthetic oils are so slippery that they can prevent the proper break-in of new engines; most oil 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 synthetics. The slippery synthetic oils get past these worn parts easily. If your car is leaking oil past old seals you'll have a much greater leak problem with synthetics.

Consider your type of driving. 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. Cars with synthetic oils may show increased fuel economy in highway driving, due to less internal friction.

If synthetic oil is used, it should still be replaced at regular intervals as stated in the maintenance schedule. While the oil itself will last much longer than regular oil, pollutants such as soot, water and unburned fuel still accumulate within the oil. These are the damaging elements within a engine and must be drained regularly to prevent damage

Vehicles 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 cars, the much greater cost of synthetic oils may not be worth the investment. Internal wear increases much quicker, causing greater leakage.