Oil question

volaredon said

Thanks. So what's the difference between an sae 20w20 and a straight weight sae 20??? Which temp is a straight weight rated at? Hot or cold? And what temp is the cold rating vs what temp is the hot rating?

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SAE 20W-20 and SAE 20 are both straight weights. The difference is that 20W-20 also meets the cold weather pour and pump tests. That earns it the 20W part, in which the W stands for winter. 20 is kind of unique in that it has both winter and summer definitions.
The tests for cold weather ratings are well below 0°F. The oil is chilled to 30 or 40 below, if I remember correctly. The hot tests are performed at 100°C. Those are viscosity and HTHS, and all four tests make up SAE standard J300. Let me see if I can find a write up that can explain it better than I can.