See Figure 1
The Society of Automotive Engineers (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.
Multi-viscosity oils (10W-30, 20W-50, 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 touring.
The American Petroleum Institute (API) designation indicates the classification of engine oil used under certain given operating conditions. Only oils designated for use Service SF or Service SG should be used. Oils of the SF/SG 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 by-products of combustion, are neutralized. Both the SAE grade number and the API designation can be found on the side of the bottle.
Diesel engines also require SF or SG engine oil. In addition, the oil must qualify for a CC rating. The API has a number of different diesel engine ratings, including CB, CC, and CD. Any of these other oils are fine as long as the designation CC appears on the can along with them. Do not use oil labeled only SF/SG or only CC. Both designations must always appear together.
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 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 some people feel that the synthetics are so slippery that they may impede this; most manufacturers recommend that you wait at least 5,000 miles before switching to a synthetic oil. Conversely, older engines are looser and tend to use more oil; synthetics will slip past worn parts more readily than regular oil, and will be used up faster. If your car already leaks oil (due to bad seals or 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 will operate 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, you 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.
Most 1970-76 Corollas were designed to operate on regular grade fuel. The 1975-76 Corollas which were built for use in California, and all models made in 1977 and later are designed to run on unleaded fuel ONLY. The use of leaded fuel in a car requiring unleaded fuel will plug the catalytic converter, rendering it inoperative. It will increase exhaust back-pressure to the point where engine output will be severely reduced. In all cases, the minimum octane rating of the fuel used must be at least 87. All unleaded fuels sold in the U.S. are required to meet this minimum octane rating.
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 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 buildup, which will in turn change the compression ratio. If your engine pings, knocks or runs on, switch to a higher grade of fuel. Sometimes just changing brands will cure the problem. If it becomes necessary to retard the timing from 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
Corolla Diesels require the use of diesel fuel (obviously). At no time should gasoline be substituted. Two grades of diesel fuel are manufactured, #1 and #2, although #2 grade is generally more available. Better fuel economy results from the use of #2 grade fuel. In some northern parts of the U.S. and in most parts of Canada, #1 grade fuel is available in the winter or a winterized blend of #2 grade is supplied in winter months. When the temperature falls below 20°F (-7°C), #1 grade or winterized #2 grade fuel are the only fuels that can be used. Cold temperatures cause unwinterized #2 to thicken (it actually gels), blocking the fuel lines and preventing the engine from running. There are a few cautions to keep in mind when dealing with diesel fuel:
It is normal that the engine noise level is louder during the warm-up period in winter. It is also normal that whitish-blue smoke may be emitted from the exhaust after starting and during warm-up. The amount of smoke depends upon the outside temperature.