oil viscocity what do the numbers mean?

i know this has been asked before but i am confused. temporarily...
what is the first # and what is the sencond#
higher number is thicker?
first # is warm
second # is cold or w for winter is this
right..?

The higher the number, the thicker it is. The first number is when cold, the second is when it's hot. Now, viscosity is a function of temperature too.
If you had a graph of viscosity vs. Temperature of straigh 30 wt, it would slope down since it gets thinner when hot. Most straight weight oils have the same slope on that graph. But a weight such as a 10w40 has a less steep slope in that when it's cold it acts like cold 10wt, but when hot, acts like a hot 40 wt.
Hope that helps.

Check out this information on the API doughnut.

web page

http://www.bobistheoilguy.com/

thats why i like this site
thanks

The 0W, 5W, 10W number is the SAE viscosity defined by the SAE J300 specifications. The test used here is the cold cank simulator which tests the oils ability to permit a satisfactory cranking speed under severe cold conditions. A 0W is tested -35, 5W at -30, 10W at -25 and so on. The other number is the kenematic viscosity tested under ASTM D445 measured at 100'C.