Whether or not you should let your car warm up on a cold morning is a bit of a thorny issue, and really depends on the age and type of car, but generally the idea is that instead of warming up your engine before driving off you should immediately begin driving. There are a few reasons for this. Let our team at BMW of Freehold tell you why.
Lubrication
The oil pump in your car is connected mechanically to the engine, and that means that when the car is idling the oil pump is not working very hard. This can lead to insufficient pressure in the oil system at a time when oil pressure needs to be high, as overnight most of the oil has dropped from the top of the engine to the bottom. Oil delivery galleries and pipes may be empty and that’s why lots of engine wear occurs in the period just after start-up.
Virtually all modern cars have notices in the handbook that the best way to warm the engine up is to immediately begin driving, but limit the engine speed until everything is warm. Your radiator water will always warm up quicker than your oil, so if you have a radiator water temperature gauge your oil temperature will lag behind that for some time, as long as fifteen minutes or more. Generally though, you don’t need to worry too much about this unless you’re about to start running the engine right to its redline. Just drive so the revs don’t exceed 2/3 of maximum for around 10 minutes and you should be OK.
Cabin heating
In the good old days an engine would run hot even while idling and provide plenty of heat for the ventilation system. These days, however, engines have become so efficient that at idle they produce little excess heat. This is especially true for diesel engines, and indeed some European car makers have special diesel burning heaters to heat up the interior of the car in very cold conditions. A modern car will not warm up enough to heat the cabin at idle for an extremely long time. Driving the car, however, makes the engine work a little bit harder and make the heating system (which uses heat from the engine’s cooling system) kick into action much sooner. If you live somewhere where it gets really cold, you can buy a car with heated seats, and in some premium brands, a heated steering wheel, which goes a long way to making you feel comfortable.
Fuel Consumption
Generally an engine will not consume more than three quarters of a gallon of fuel per hour, but it’s still fuel that could be used for going further, and indeed many car makers are producing cars with engines that automatically shut down when the car is stationary, and start up again when you push on the throttle, saving fuel that would normally be wasted.
In general, the advantages of driving the car immediately, at a reasonably stable pace, outweigh any advantages from warming the car up before driving away. The only exception is perhaps in areas that get so cold that the car comes with an auxiliary electrical engine heater you plug into the house electrical supply so the oil does not freeze overnight.
