After starting to read through the "Synthetic Oil" thread, I realized that was a chore I didn't have time for. There were some misconceptions that needed clearing up though.
5W-30: This means the oil behaves like 5 weight when cold (40 deg C, or 104 deg F) and 30 weight when hot (100 deg C, or 212 deg F).
You can visualize this comparison with a couple of funnels - a wide one for cold and a nrrow one for hot. The number is how long it takes for the oil to flow through the funnel. 5w-30 takes e.g. 5 seconds thorough the wide funnel when cold, and 30 seconds through the narrow one when hot. A straight 30 weight takes 30 seconds through both.
When it's hot, the engine doesn't know the difference between 5w-30, 10w-30, or even straight 30 weight.
When it's cold, a 5w-30 will flow faster to where it needs to be when you first crank it up.
Steve
5W-30: This means the oil behaves like 5 weight when cold (40 deg C, or 104 deg F) and 30 weight when hot (100 deg C, or 212 deg F).
You can visualize this comparison with a couple of funnels - a wide one for cold and a nrrow one for hot. The number is how long it takes for the oil to flow through the funnel. 5w-30 takes e.g. 5 seconds thorough the wide funnel when cold, and 30 seconds through the narrow one when hot. A straight 30 weight takes 30 seconds through both.
When it's hot, the engine doesn't know the difference between 5w-30, 10w-30, or even straight 30 weight.
When it's cold, a 5w-30 will flow faster to where it needs to be when you first crank it up.
Steve