Motor Oil....?

While Changing my oil today, I was looking at the quart, I noticed it said 10W 40. I know what the 10 means but what does the 40 mean?Motor Oil....?
http://www.atis.net/oil_faq.html Scroll down to Section 2, then read down 4 or 5 paragraphs, it's all explained there. I hope this helps.Motor Oil....?
10W 40 means the oil has the viscosity of standard 10W oil when cold and the viscosity of 40W oil when hot. This is what multigrade oil means.
Finish reading it... Its on the back also.





10w 40 Is the Weight of the oil over all and what temp's it covers from the negative (COLD) to HOT...

skin infection