Although GM claimed that Mobil 1 5W-30 is adequate for the Eaton blowers, we have not been impressed with the results over the years. We spent a very long time hunting for a better oil, and we found it! The oil we now use and sell is a special synthetic blend of oil with properties much better suited for this job than engine oil. The biggest problem with engine oil is that it has a high coefficient of thermal expansion. In an engine, this isn’t a problem because they are not a closed system. However, in a supercharger that is closed and that operates at over 16k rpm, traditional engine oil expands and causes unnecessary internal pressure. Our blend has a very low coefficient of thermal expansion, and in addition to the other properties, makes it ideal for use in superchargers.