oil pressure
The higher the number, the thicker the oil.
One way to think of a multi-grade oil is like this example. A 20W-50 has viscosity more like a 20 'weight' at cold temperatures, and the same as a 50 'weight' at hot temperatures. Technically this is not exactly correct, but its basically right.
Here's a visual comparison of the viscosity of Brad Penn's straight 40 oil and some multi-grade 40s.
Look at the viscosity of each at 68*F.
At 68 F, the viscosity of the straight 40 is around 500 centi-Stokes.
While the viscosity of the 15W-40 oils are around 350 centi-stokes.
and the Rotella T6 5W-40 is only about 225 centi-Stoke.
Once they are up to 212 * F, they all must be between 12.5 to 16.3 cSt. In this example all are 15.5 cSt except for the 5W-40.
Yes. Use an oil with same hot viscosity as now, but that has a lower cold temperature viscosity.
Yes Warm oil flows better than cold. The only thing you had backward is how the SAE numbers work.
The higher the number, the thicker the oil.
One way to think of a multi-grade oil is like this example. A 20W-50 has viscosity more like a 20 'weight' at cold temperatures, and the same as a 50 'weight' at hot temperatures. Technically this is not exactly correct, but its basically right.
Here's a visual comparison of the viscosity of Brad Penn's straight 40 oil and some multi-grade 40s.
Look at the viscosity of each at 68*F.
At 68 F, the viscosity of the straight 40 is around 500 centi-Stokes.
While the viscosity of the 15W-40 oils are around 350 centi-stokes.
and the Rotella T6 5W-40 is only about 225 centi-Stoke.
Once they are up to 212 * F, they all must be between 12.5 to 16.3 cSt. In this example all are 15.5 cSt except for the 5W-40.