The general rule of thumb for air compressor oil is to use oil made by the same manufacturer as the compressor. Whilst this is a good guide to follow sometimes it can be hard to get your hands on a specific make of oil; especially if time is a factor. That is why it’s important to know the optimum type of oil for your particular air compressor.
First of all, you need to use non detergent oil. This is because the engine inside an air compressor doesn’t make combustible materials so does not need detergent to get rid of any residue. These days, there are two types of compressor oil – regular and synthetic. For everyday household use regular oil is fine. It is also cheaper than synthetic oil. This is used for air compressors on a larger, industrial scale.
In general, air compressors will run fine on 30 weight oil. This oil works best at temperatures of between 35 and 100 degrees. For anyone using a compressor in cooler temperatures 20 weight oil would work better. An easy way to remember is the hotter the temperature, the higher the weight.
Although synthetic oil can be more expensive than regular oil, it does feature many advantages. Completely synthetic 30 weight oil will work in freezing temperatures and give your equipment a longer shelf life. Another big advantage is the fact you hardly ever have to change the oil. An air compressor running on synthetic oil can run for up to 8000 hours before an oil change is needed! If you cannot afford synthetic compressor oil you could always use synthetic motor oil (as long as it is non detergent).
Even though the motor oil is not made specifically for use in the air compressor they can run for years and years on it. While it is probably best to use the manufacturer’s own oil there is certainly no harm in using non-detergent motor oil as a substitute. It will do no damage to the air compressor.
Last of all, this may be an unorthodox suggestion, but, if there really is no other oil available then regular motor oil can be used in your compressor. If it is all you have then regular oil, even with detergent, will work. The compressor may not run quite as efficiently but it won’t damage it either.