My bimmer was hard to start in the cold last year, so this year before the winter hit I installed an oil pan mounted warmer. Similar to a heating pad that sticks to the oil pan, from testing this with my temp probe the oil temp would go from 35*F to 110+*F in about 2 hours, this will all depend on things like wind ect.. (drastically cutting down cold start wear).
Pre-warming the oil is the best for your motor IMO. But your coolant will not be as warm as with a block heater, so you won't have full heat in the cabin when you go out to start the car (but personally I'm more worried about cold start engine wear than having the heater right away, plus I have remote start on the bmw). This year I have had no issues starting up in the cold. Plus I have the peace of mind knowing the oil is warm and flowing, were as before when starting in the cold my sphincter would be clinched knowing how cold and thick the oil was on start up.
I have this plugged into a timer to come on 2 hours before I start my car in the morning. You can leave it plugged in over night, but I have not done any testing for more than 2 hours. I got mine from a company called
Proheat, I found out about this product from over the road Simi-truck drivers that swear by these heaters.
IF YOU ORDER FROM THIS COMPANY, call them! as their online order form IS NOT SECURE. I found out the hard way, but this was not the Proheat company that ripped me off.
A couple of down falls of block heaters are, they impede coolant flow when the motor is running as the heating element is in the passage way, and the oil is still cold when you start up.
I've
heard (take it for just that, hear-say) that they can create hotspots that can cause warping. :dunno:
