by coyote » Wed Oct 09, 2013 11:11 am
0W, 5W, 10W, etc relate to the viscosity of the oil at 40C. Even a 0W on a 35C day is much thicker than ideal and you should take it easy until it heats up!
The second number relates to the viscosity at 100C (operating temp).
It's been said enough times on this forum that people should know this.
The lubrication system, bearings, pistons, etc on these cars has been designed to work with a 5W30 oil. As long as your cooling system is operating correctly, operating temp will be basically the same. Refer back to the second line of this post to see what that means.
All the old wive's tales that were born out of the compromises of mineral based oils are made defunct by modern synthetics.

** Team Tony **