Let engine idle before driving??
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This is a discussion on Let engine idle before driving?? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Since getting my WRX last year I have got in the habit of letting my cars idle for a few ...

  1. #1
    Registered User tesla317's Avatar
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    Aug 2012

    Let engine idle before driving??

    Since getting my WRX last year I have got in the habit of letting my cars idle for a few minutes before driving. I've been doing some research and surprisingly found mixed views on the idea.

    The whole idea of letting a car idle is to bring it up to optimum operating temp to reduce wear on the engine. However, I've read that it takes considerably longer to do so when idling, causing more wear and being inefficient.

    So they say it's better to idle about 30 seconds and drive lightly for the first few miles, which will bring the car to optimum operating temp much quicker, thus reducing engine wear. Also the cat. needs to run at a higher temp to be more efficient, which when ran colder causes more build up.

    I just simply wanted to protect my car best as possible, and was surprised at reading a lot of this. Of course I didn't see any real data supporting these claims, and I'm no mechanic or engineer. Maybe I'm reading to much into this, but none the less it was interesting.
    Last edited by tesla317; 09-08-2013 at 10:29 AM.

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  3. #2
    Master Baiter EJ257's Avatar
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    Get in the car
    Turn key to "ON" position and listen for the fuel pump to finish priming
    Start car
    Adjust radio, mirrors, windows, apply sunglasses, put seatbelt on, light cigarette, etc. (whatever else you do before typically beginning your trip)

    The "operating temp" thing is to make sure you're not beating the crap out of the car until the coolant and oil are up to temp. Typically, I keep RPMs at/below 3-3.5K until coolant is up to temperature. After that, I'll keep them at/below 4-4.5K until oil is up to temperature. Then it's whatever I feel like...

    Without an oil temperature gauge, you're unable to know when it's at temp. However, as a general rule, I've found that oil takes ~2X as long as coolant to get to temp.
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  4. #3
    Registered User Motoxdude6's Avatar
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    Jan 2013
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    on a cold start, i always let my car idle to get to a decent temp. normally ill wait till i start to see my temp gauge rise, to the first or second line, and then begin my drive, as it only take a very short amount of driving to get to normal operating temp. but thats just me. just dont be one of those noobs that, as soon as ur done turning ur key, throw it in drive and take off before the initial high rev declines to normal idle rpm. i feel so bad for people cars that as soon as the engine is running they are already driving off, before it can drop down the rpms

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  6. #4
    Registered User Zitro's Avatar
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    Jul 2013
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    If I waited for my rpms to drop to regular operating rpms, I'd be waiting a long time. On a cold start im usually hovering around 1.6k and it takes several minutes to settle down to the normal 700-750 range. Caught me off guard at first, as my previous car would calm down to it's normal idle of 650 in less than a minute.
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  7. #5
    Super Moderator (Actually a SuperSpy) SD_GR's Avatar
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    Let engine idle before driving??

    I just drive off normally as stated in the manual.

    Idling adds wear without covering any distance and does not warm up the gear or diff oils.
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  8. #6
    MAINEiac 11blackSTi's Avatar
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    The only time I ever let my car idle for any significant amount of time before I drive is when it is winter and the car has been sitting in less than 20 degrees for a significant amount of time. In that case, I simply wait for the car to begin to get warm (often times long enough for me to clear the windows of snow). That is simply to get the car to begin to actually get warm inside though. Other than that I also follow the procedure specified above by EJ257.

  9. #7
    Registered User RichD514's Avatar
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    Jun 2012
    Long Island, New York, United States
    Quote Originally Posted by Motoxdude6 View Post
    . just dont be one of those noobs that, as soon as ur done turning ur key, throw it in drive and take off before the initial high rev declines to normal idle rpm. i feel so bad for people cars that as soon as the engine is running they are already driving off, before it can drop down the rpms
    that's basically how I've driven every car I've owned, and surprisingly enough... None if them have blown up in my face.

    Idling the engine for extended warm-up just wastes fuel. Just prime the pump, and take it easy the first few minutes.

  10. #8
    I Drink & I Know Things JaySin's Avatar
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    We all have opinions on this, but 30 seconds before driving is fine. Just don't beat on it until it's warmed up a little if it's REALLY cold out. I'm feeling opinionated today.

  11. #9
    Registered User wreckingball man's Avatar
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    Jul 2012
    Rocky Top
    If it's really cold I may let it idle a bit, as long as it takes to clean off my windshield. If it's summer, I start it and turn on radio, adjust things, put on sunglasses and go. Just drive off and take it easy until it warms up for the first few miles. And turning the key, I always wait until I hear the fuel pump stop priming and never start it with the A/C on.

  12. #10
    Pro Manscaper Mikie13's Avatar
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    I get in my car, turn the key, engine starts...and I drive away. Never had a problem in 13 years of driving with any of my 7 cars I've had.
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