How to Choose Oil
It is not hard to figure out which oil to use in your car if you know what the viscosity and API ratings mean on the label. If you have ever checked the engine oil, then the proper type of oil to use is usually stamped on the oil dipstick. You might see something like "5w-30 SF" stamped into it. That is the oil to use for your engine, nothing more and nothing less. It is common sense that engine oils have different thicknesses, which would be the viscosity rating. Most modern oils even have multiple viscosity rates, as the temperatures rise. The viscosity rate is the numbers by which the engine oil is called, like 10w-30. The other rating that you need to look at is the API seal. API stands for American Petroleum Institute when referring to engine oil. It is the rating of the technologies used to make the oil, and its quality, that this rating is based on. Engines that run on gasoline have the designation of the letter “S”. The technology and quality rating is designated by the second letter in that rating, in alphabetical order. So, engine oil with the rating of “SA” would not be as good as engine oil with an API rating of “SF”. Diesel engine oils are rated the same way with the quality, but the first character is a “C”. This means that diesel engines will have an API rating that looks like “CA” or “CF”. Now that you know how the ratings work, let’s look into the choice of synthetic, synthetic blend, or conventional engine oils.
If you are talking about whether to choose synthetic engine oil, synthetic blended engine oil, or conventional motor oil, you should always use the one that is specified by the manufacturer. There are other articles that explain why to only use manufacturer recommended engine oil types, and they do it in great detail. To sum them up though, when the engine was designed, it was with very specific engine oil in mind. Different oils have different properties and it can harm the engine, according to the way it was designed. Things like make the engine smoke or leaving gasoline in the oil pan (which eats the oil and destroys engine parts) are common to engines that use the wrong oils. In fact, if you have an older engine that was designed to use conventional oil, and start using synthetic engine oil in it, the oil pump will be damaged. That might be why the oil pressure goes up and down on your gauge, huh?
