Quote:
Originally Posted by BHarvey
If your car is designed around a 8.5cst (xW 20) oil at an oil temp of 212f, then at 104f the oil is 30-48 cst, or WAY thicker than even a xW60 at 212f.
Too thick and it kills mpg...
|
When I was in college (late 90's) we had done a lab experiment with engine oil viscosity. IIRC, we used a conventional 10W-30 and a synthetic 10W-30, chilled both to -45°F (We just left them outside overnight...) and measured the viscosity as we slowly heated to 212°F.
Even though both were the same viscosity rating, there was a huge difference at extreme temperatures. I've forgotten the numbers exactly, but remember the synthetic being similar in consistency to honey at -40°F, but the conventional oil was VERY thick, almost a solid, kind of like Silly Putty.
Even at room temperature, there was a big difference between synthetic and conventional. It wasn't until it got close to boiling (of water) that they were about the same.