the first number is viscosity at lower temperatures. some choose to use lower weight viscosity for colder temps, but using a synthetic with a pour point of -46 degrees makes it not matter a whole lot i think.

 

This is a Honda of Japan chart:

http://www.honda.co.jp/parts/hop/oil/next02.html

The translations: A circle means good. An X means bad. The double circle means best. 10W-30 is good and 5W-40 is best.

I beleive that 5W40 is available only with synthetic formular, no dino oil with this viscosity grade. Since the temperature in So. Cal. is mild year round, you can use 10W30 if it is eaiser to find and if it is cheaper than 5W40. Costco sells 6 quarts case of Mobil1for about $24, but only in 10W30 or 5W30. I'd never saw 5W40 Mobil1 in Costco.

 

[QUOTE=Wisconsin S2k,May 26 2005, 02:45 PM] the first number is viscosity at lower temperatures.

 

Mobil1 10w30 in So Cali is just fine!

 

It is the oil viscosity or oil weight. A low number indicates a relatively thin oil while a higher number is a thicker oil. Your car needs different ranges. Cold oil is thick and resists flow, when heated it becomes thin and runny. Thick oil can cause problems starting a car, while too thin of an oil can break down. Your car needs an oil that is thin enough for starting and thick enough to maintain lubrication when hot.

 

THANK YOU! Now that's an explanation a chic can understand.

 

feistyS2K, I am sorry. I did not know that you do not know much about oil grades.
Multigrade oil formular: xx W yy, xx is how the oil flow at cold start after the car is parked for a long time, such as overnight. The lower the xx, the faster it can flow. Most of the oils you can easily buy at any autopart stores in America has the lowest xx of 0 and highest of 20. The other numbers, yy, is the viscosity of the oil at operating temperature, after the car had been run for a while, likes 20 minutes or so. The higher the yy, the higher temperature it can operated before breakdown. This numbers yy, available widely in America, can be 20 or 30 or 40 or 50.
Popular oils in America are: 0W20, 0W30, 0W40, 5W20, 5W30, 5W40, 10W30, 10W40, 15W40, 15W50 and 20W50.
In European and elsewhere, you can find these oils: 5W50, 10W60 and other multigrade oils.
Many newer cars have very long oil change interval, up to 1 year or 15k miles. Many European cars, such as Mercedes Benz's recommended oil is 0W40 for most of its cars.
The weather in California is mild all year, if your driving is mostly highway, then 10W30 is the prefered oil for your S. If your driving is mostly on city streets, 5W40 is better for stop and go and long idle times. And either one is recommeded by Honda for S2000.