Re: oil viscosity question....

Posted by Fish'n Jim On 2016/11/12 10:06:08

It's not that easy, but for sake of not causing a long thread and millions of questions, the "W" means it's "cold cranking" rated. The problem is they measure each weight for "W" at a different temperature to preserve the "pumping" rate. So the kinematic viscosity is a curve not linear. Also, depends alot on the additives.
If you said SAE 30 and SAE 50, it would be simpler. The number is related to kinematic viscosity. The dynamic viscosity could vary alot.
One of many links to read up on.http://www.machinerylubrication.com/Read/411/oil-viscosity