West Texas Intermediate oil slipped on Friday and traded close to its weakest level in a 30-day period on speculation that the U.S. stimulus measures may be trimmed further as the country's economy improves. WTI for delivery in February traded 13 cents lower at $95.31 per barrel on the NYMEX as of 2:17 p.m. in Singapore after it dropped $2.98 to $95.44 per barrel yesterday.