I'm having trouble explaining myself.
A straight weight oil, such as SAE 30, is actually "xW-30" where x is not known to the consumer. Perhaps it varies from batch to batch. Perhaps the x is too large. There has to be a result of some sort when you test the oil in a "cold test" machine. What would be typical?
Have you ever heard of someone putting a straight weight oil in the "cold test" machine and determining its winter weight number?
I'm just curious about a typical result. 25W30? or ?
30W oil is 30W30.
20W oil is 20W20.
If it is a straight weight weight, it is the viscosity of that weight oil at all temperatures.
Just to be clear, it is not the *same* viscosity at all temperatures, it is the viscosity of that weight oil.