Cyril Huze Blog – World's Number One Source For Custom Motorcycle News

Question: I am still getting questions about multi-weight lubricants, so here’s an explanation in one short paragraph.

Answer: A multi-weight oil is an oil formulation that acts as if it has two different viscosities, depending on the temperature. At the lower test temperature 40C, it flows as the first number would indicate, and at the higher test temperature 100C, it flows as the second number would indicate. This multi-weight nature is made possible by the addition of long-chain polymers to the oil, which are coiled up when cold, but straighten out when hot, and thus change the flow characteristics of the oil. Thus a 10w50 oil will flow like a 10 weight oil when at 50C  fairly thin, but will not thin out more than a 50 weight oil would when hot 100C. Provided By Spectro Oils