Originally Posted By: stygz
Originally Posted By: 440Magnum
I keep saying:
-The 2nd number (the one after the "w") is the oil grade, and reflects viscosity at operating temperature. (10w30 is a 30-wt at operating temp, so is 0w30 and 5w30 and SAE30, they're all nominally the same in your engine when its at full operating temperature, barring product-to-product variation and tolerances in the spec.)
-The first number is a rough measure of how much the oil thickens as it cools down. 10w30 nominally thickens more than 5w30, and 5w30 thickens more than 0w30. But the temperature at which that first number is determined is REALLY low, so if (for example) it only gets down to 10deg F in your area, a 5w30 and 0w30 may do exactly the same thing and the 0w30 would only have an advantage if it kept getting colder.
-It is NOT a case of "its a 10 weight when its cold and a 30 weight when its hot."
If my summer temps were to get down to 70 degrees at night a 0w30 and a 5w30 would have the thickness at start up? Considering the 0w30 for start up protection.
Yeah, 5w30 or 0w30 doesn't really matter much when "cold" is room temperature. Shannow posted a link to a video showing a cold pour test of different oils at -40F. The 0w30 is a HUGE advantage there... 10w30 was practically grease, and the straight 30 was a block of candle wax.
Found the vid link. Go to the 2:20 mark:
Cold oil video
Originally Posted By: 440Magnum
I keep saying:
-The 2nd number (the one after the "w") is the oil grade, and reflects viscosity at operating temperature. (10w30 is a 30-wt at operating temp, so is 0w30 and 5w30 and SAE30, they're all nominally the same in your engine when its at full operating temperature, barring product-to-product variation and tolerances in the spec.)
-The first number is a rough measure of how much the oil thickens as it cools down. 10w30 nominally thickens more than 5w30, and 5w30 thickens more than 0w30. But the temperature at which that first number is determined is REALLY low, so if (for example) it only gets down to 10deg F in your area, a 5w30 and 0w30 may do exactly the same thing and the 0w30 would only have an advantage if it kept getting colder.
-It is NOT a case of "its a 10 weight when its cold and a 30 weight when its hot."
If my summer temps were to get down to 70 degrees at night a 0w30 and a 5w30 would have the thickness at start up? Considering the 0w30 for start up protection.
Yeah, 5w30 or 0w30 doesn't really matter much when "cold" is room temperature. Shannow posted a link to a video showing a cold pour test of different oils at -40F. The 0w30 is a HUGE advantage there... 10w30 was practically grease, and the straight 30 was a block of candle wax.
Found the vid link. Go to the 2:20 mark:
Cold oil video
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