2002 Toyota Camry Smoke at start up

Due to rising gas prices, I recently purchased a Camry for work purposes. The car is a 2002, four cylinder, manual transmission with about 85,000 miles. The car performs to mpg standards, but at cold start up smoke comes out of exhaust at the start but then is gone. Although not due for its emission test, I had it tested to try to determine the smoke source. The car fully passed. Once running and warm, I have found no smoke problems. At initial start, sometimes the crank up takes a short period, but for the most part I have had no problems. Smoke is grey to greyish blue in color. Any ideas what this could be from and what the cure may be, repair or additives? Thank you.