according to some auto magazine. You don't have to warm your car to optimal temperature before you take off. Just warm your car for about one and a half minute (to let all the fluid and oil going), then drive slowly, don't rev the engine up. this is the most efficient way too, coz it doesn't waste lots of gas to warm up the car. I lived in edmonton, we have about 9 months of winter and it is freezing cold all the time...I follow this method, nothing goes wrong (I do plug in my block heater all the time during winter & use fully synethic oil)