Quote:
Originally Posted by ZDan
Found searching on 0w20 5w30 viscosity vs. temperature. It's just an illustration, the point is the same whether those curves are perfectly accurate or not. Different specific oils may have somewhat different curves, but the general trend is the same. Higher temperature, lower viscosity...
The point is that *any* oil is going to thin out as temperature goes up. At 270F, if you want your oil's viscosity to be closer to what the factory-fill 0w20 is at normal operating temps (~190F-220F), you'll need to run heavier oil. This point is true whether or not the curves posted are 100% accurate. A 30-weight oil is going to have higher viscosity at 270F than a 20-weight, and 40-weight higher still.
What the manual specifies doesn't really apply if you're tracking at 270F+ oil temps. But some manuals still encourage use of thicker oils at higher operating temps...
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I was trying to point out that while you are correct that oils thin as they go up in temp. Saying you need to run so and so weight is 100% BS without actual proof backing that up. Which is why I asked where that graph came from.
I will take a look at the Widman site after I get Home from work and Update this post then.