Oil Pressure Issue?

RustyRatRod said

Well......sorta. The first number is the weight before the oil reaches operating temperature. Once there, it is the second number.

I have assumed for years that the "W" stood for winter, but it does not. At least from what I can dig up on the net. The best that I can find is that it means "when cold" or before operating temperature.

At least, that's what I have gathered from most of the oil sites.

So basically, if you have 20/50, it is essentially 50 weight because that's what it is when warmed up.

At least, this is what I have inferred from reading. I could be slam wrong.

Click to expand...

No. This is correct. I'm up in canada and we have to pay close attention to how the oil viscosity works.

Not to repeat RRR. But the number before the W is its rating when cold. After the W is at that oil's operating temperature. Note though that different oils have different operating temps.

EX: 5W30
5 When cold
30 When at operating temp

The W thing is just an old hang around because it was designed to work in winter and summer. So guys used to call it 5 WINTER then whatever summer oil. Which is a misnomer in itself. Oil is considered cold whenever it isn't in its operating temperature range. Even if its 30+ (Celsius) out. It's technically still "cold" oil in the pan. It just warms up faster than when it's -30 out.