Quote:
Originally Posted by rbrowning
I guess the question I would like to see a definitive answer to is:
Is the fuel consumed in running an engine at idle for a minute more than offset by the reduction in fuel consumed because of the warmer oil?
Yes, obviously the fuel consumed is "wasted" because it doesn't move you down the road, like the example of the winglets on the airliners. They add drag, they produce no lift therefore they are bad, right? Wrong, they improve the lift by keeping the airflow over / under the wing without it slipping off the end of the wing. Can the fuel burnt by idling the engine a minute improve the efficiency when the engine is under load enough to pay for itself?
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It shouldn't be too hard to test. Either with a ScanGauge or without. Start up the car & take off without warming it up & drive it for 5-10 minutes or so on a given route, come home & park. Next morning, repeat. Next morning, repeat again. Etc. Check mileage. Then do it again, but let "warm up" for 1 minute (60 seconds on the stopwatch) each time before taking off. Check mileage. And there will be the answer - It'll either help, hurt, or have "inconclusive results"?
With a ScanGauge, just do a "trip" average "current-reset" each time & note it. Then you can even spend the rest of the day driving "normally". But check it each time you do a cold start in the "morning".
Without a ScanGauge, there would probably have to be about 10 cold starts & drives on 10 different days for each the "no warm-up" and "with warm-up" tests checking mileage at the gas station when filling up. Obviously, it would be very important to drive the exact same number of identical trips for each the "warm-up" and "no warm-up" halves of the test and to fill up to the exact same level both times - same station, same pump, same time of day, etc, etc,