I know that many of you are tired of hearing me say that viscosity is the single most important property of any oil. It’s a mantra I learned as a rookie in the oil industry and one that I believe. The thing is, how do we know which viscosity is the correct one? For over one hundred years there has been an SAE standard, SAE J300, that provides a relatively easy way to help the end user choose. However, in most cases the end user needs guidance on what viscosity is right for their application.
I usually go back in time to lay the groundwork for my comments, but this time I’ll refrain. Besides, if you’ve saved your old copies of Lubes’n’Greases you can probably find one or two columns that go over viscosity in more detail. There is a story about viscosity that I would like to delve into that concerns the decrease of viscosity over the past at fifty years.