Motor oil in vehicles play a big role in keeping an engine operating under the right temperatures. The viscosity numbers will tell immediately the range of temperatures it should be ideally used. Lower numbers, especially those with a "W", means those are for extreme cold weather like winter which the "W" represents after the number. Normally, those in the cold regions where they have winter season, they use motor oils between "0" to 15 or 20 variable viscosity. The "0" means the oil will be in this viscosity during cold starts. The oil turns more viscous as the engine runs to operating temperatures on that weather condition. The lower viscosity allows for the engine to crank with ease under extreme cold weather. It follows, therefore, that in warmer climates or regions, motor oils being used range between the variable viscosity of 10 to 30 or 40. Engines that operate under higher temperatures should be using higher viscosity oils.
Another consideration to be noted when using motor oil is the letters that you find, sometimes before or after the viscosity numbers. Commonly, two letters that would either start with an “S” or a “C”. The letter “S” stands for spark combustion, meaning it is for vehicles that have Spark Plugs that make for spark combustion in Gasoline Engines. The letter “C” stands for Compression Combustion which is the case for Diesel Engines. Diesel engines do not have spark plugs but instead compresses air then injects diesel to initiate combustion. Why is there a distinction between gasoline and diesel engine motor oils? Generally, diesel engines run hotter and a little bit ‘dirtier’ than gasoline engine. Diesel engine motor oils have more ‘detergents’ or cleaning agents in them. So using gasoline engine motor oil for diesel engines is not advisable. You can only do this under emergency situations.
As for the letters after the first “S” or “C”, depends on the cleaning ability and protection ingredients with the motor oil. Usually, those with an “A” are the least, like SA or CA, has the least ingredients. Those with B, C, D, and the succeeding letters after, will mean having better cleaning and protection ingredients in them.
How do you deal with High gas prices
Driving with Automatic Transmission