Originally Posted By: kingrob
Idling supposedly kills cars, but I've never seen any compelling evidence to convince me of such. If it's cold outside, I see absolutely nothing wrong with idling your car to operating temps before you get in it. It's much better than getting in and running the guts out of it to get it up to temp IMO.
Last year my Daughter did a project for her science fair.
Subject? Idling vs driving for warm up.
Using a scan gauge and 3 different cars (2002 Silverado V8, 2007 Outback H4 and 2005 Toyota Corolla I4) she sat with stop watch, outside temps the same and the scan guage and recorded that idling for 10 mins the coolant temp got up to (the data was the same in all cars, but I'll use the Subaru here) 135 degrees. Drive the car for 5 mins and the temps were up to 160 degrees. After 10 mins of PRODUCTIVE fuel usage the coolant temp was up to 192 degrees. Took over 17 mins to get up to 170 degrees when Idling (ie NON productive fuel usage)
After 20 mins the coolant temp still was not 192 degrees with idling. After 20 mins I stopped the test.
Same with the Toyota and Truck. The truck took longer to heat up and the toyota was in the middle. Subaru was the quickest.
Not to say what all the fuel in the system will do.
Lets put it another way, 3 1/2 mins after starting and driving the coolant temp was the same as 10 mins of idling. So if you want heat, operating it easy is much quicker than idling.
Take care, Bill