Technical aspects of automobiles

avoiding cold starts

First, are these assumptions correct?
(1) Starting a car when the engine is cold puts alot more stress on it
than when it’s already warm.
(2) And the colder it is, the more stress.

Because i’ve always assumed the above, I do the following, but I want
to verify whether it’s really worth it and doing any good…noone else
that I  know does this.

If I know I"m going to cold-start and then drive to  a destination that
is only a short distance (less than 5 miles) and then a second
destination a short time later,  rather than go to the first
destination and turn off the engine off right away (before it’s reached
full operating temps, at least based on the "thermometer" on the dash),
 I’ll usually drive around a little bit more, or let the engine run for
about more minutes, before turning it off……..since I know i have to
re-start it in less than an hour to go to my second destination….so
tha when i re-start it the engine should still be warm.

Also, in other cases, if after reaching the first destination with the
engine not fully hot…., rather than turn it off, i’ll just leave the
car and let the engine run (if it’s just a short stop over, like 5
minutes) and then go on to my 2nd destination.

I’m wondering whether i’m doing any good by this.

.
posted by admin in Без рубрики and have Comments (13)

13 Responses to “avoiding cold starts”

  1. admin says:

    Modern engines with modern oils are way less sensible to cold starts.
    What you are doing does not do any noticeable good for your engine, and
    technically does not hurt either. It hurts your wallet and our ecology,
    though.


    MishaA
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  2. admin says:

    - Hide quoted text — Show quoted text -

    mac wrote:

    > First, are these assumptions correct?
    > (1) Starting a car when the engine is cold puts alot more stress on it
    > than when it’s already warm.
    > (2) And the colder it is, the more stress.

    > Because i’ve always assumed the above, I do the following, but I want
    > to verify whether it’s really worth it and doing any good…noone else
    > that I  know does this.

    > If I know I"m going to cold-start and then drive to  a destination that
    > is only a short distance (less than 5 miles) and then a second
    > destination a short time later,  rather than go to the first
    > destination and turn off the engine off right away (before it’s reached
    > full operating temps, at least based on the "thermometer" on the dash),
    >  I’ll usually drive around a little bit more, or let the engine run for
    > about more minutes, before turning it off……..since I know i have to
    > re-start it in less than an hour to go to my second destination….so
    > tha when i re-start it the engine should still be warm.

    > Also, in other cases, if after reaching the first destination with the
    > engine not fully hot…., rather than turn it off, i’ll just leave the
    > car and let the engine run (if it’s just a short stop over, like 5
    > minutes) and then go on to my 2nd destination.

    > I’m wondering whether i’m doing any good by this.

    Define cold.
    Cold to me is anything below 85F.  Below 50F and I don’t go outside.

  3. admin says:

    It’s better to let any engine warm up as much as possible, but leaving the
    car running (unless it is occupied) is a great invitation for car thieves.
    Many people have gone to 7-11 to get coffee on the way to work and left
    their cars running while in the store only to have it disappear while
    getting their coffee.
    Roy
    "mac" <oct3…@yahoo.com> wrote in message

    news:1163475751.898641.150440@h54g2000cwb.googlegroups.com…

    - Hide quoted text — Show quoted text -

    > First, are these assumptions correct?
    > (1) Starting a car when the engine is cold puts alot more stress on it
    > than when it’s already warm.
    > (2) And the colder it is, the more stress.

    > Because i’ve always assumed the above, I do the following, but I want
    > to verify whether it’s really worth it and doing any good…noone else
    > that I  know does this.

    > If I know I"m going to cold-start and then drive to  a destination that
    > is only a short distance (less than 5 miles) and then a second
    > destination a short time later,  rather than go to the first
    > destination and turn off the engine off right away (before it’s reached
    > full operating temps, at least based on the "thermometer" on the dash),
    > I’ll usually drive around a little bit more, or let the engine run for
    > about more minutes, before turning it off……..since I know i have to
    > re-start it in less than an hour to go to my second destination….so
    > tha when i re-start it the engine should still be warm.

    > Also, in other cases, if after reaching the first destination with the
    > engine not fully hot…., rather than turn it off, i’ll just leave the
    > car and let the engine run (if it’s just a short stop over, like 5
    > minutes) and then go on to my 2nd destination.

    > I’m wondering whether i’m doing any good by this.

  4. admin says:

    mac wrote:
    > First, are these assumptions correct?
    > (1) Starting a car when the engine is cold puts alot more stress on it
    > than when it’s already warm.
    > (2) And the colder it is, the more stress.

    I would dispute that it puts "a lot" more stress on it. Cold starts with
    modern oils of the correct grade for the climate you’re in are really a
    non-issue. Yeah, a modern engine may piston-slap like a diesel when its
    cold and sound very different than when its hot (unlike older engines
    with different piston alloys and designs that traded efficiency for
    quiet when cold,) but that’s a completely harmless sound. It would be
    far more harmful if the pistons bound in the bore when the engine was
    fully heated up.

    > Also, in other cases, if after reaching the first destination with the
    > engine not fully hot…., rather than turn it off, i’ll just leave the
    > car and let the engine run (if it’s just a short stop over, like 5
    > minutes) and then go on to my 2nd destination.

    > I’m wondering whether i’m doing any good by this.

    You’re probably doing HARM through excessive fuel dilution into the
    lubricating oil.

  5. admin says:

    > You’re probably doing HARM through excessive fuel dilution into the
    > lubricating oil.

    Interesting….I was reading in the past few years that idling doesn’t
    hurt the engine any more than driving does….but i think a LONG time
    ago I used to hear that it’s not good to idle too "long" (an hour?).

    One slightly related (to my original question)  thing I heard last
    year:    If your going to let you car sit parked (off) for a long time
    (weeks??),  you should NOT ‘t drive a short distance and then turn the
    engine off before the long parking duration….You should drive it
    until it’s fully warmed up….supposedly the condensation in the engine
    would remain there and cause rust if you don’t fully warm it before
    turning it off and letting it sit…….true?

  6. admin says:

    mac wrote:

    > > You’re probably doing HARM through excessive fuel dilution into the
    > > lubricating oil.

    > Interesting….I was reading in the past few years that idling doesn’t
    > hurt the engine any more than driving does….but i think a LONG time
    > ago I used to hear that it’s not good to idle too "long" (an hour?).

    Must have been when carburetors were the norm.  I can’t imagine
    that a modern fuel-injected and electronically controlled engine
    would have problems with idling for long periods of time.

    > One slightly related (to my original question)  thing I heard last
    > year:    If your going to let you car sit parked (off) for a long time
    > (weeks??),  you should NOT ‘t drive a short distance and then turn the
    > engine off before the long parking duration….You should drive it
    > until it’s fully warmed up….supposedly the condensation in the engine
    > would remain there and cause rust if you don’t fully warm it before
    > turning it off and letting it sit…….true?

    Modern motor oil is probably better in handling all this stuff.  Many
    (if not most) engines these days are aluminum.  I’ve never had an
    oil analysis with any appreciable amount of moisture, even when
    taken after a short drive.

  7. admin says:

    - Hide quoted text — Show quoted text -

    mac wrote:
    > First, are these assumptions correct?
    > (1) Starting a car when the engine is cold puts alot more stress on it
    > than when it’s already warm.
    > (2) And the colder it is, the more stress.

    > Because i’ve always assumed the above, I do the following, but I want
    > to verify whether it’s really worth it and doing any good…noone else
    > that I  know does this.

    > If I know I"m going to cold-start and then drive to  a destination that
    > is only a short distance (less than 5 miles) and then a second
    > destination a short time later,  rather than go to the first
    > destination and turn off the engine off right away (before it’s reached
    > full operating temps, at least based on the "thermometer" on the dash),
    >  I’ll usually drive around a little bit more, or let the engine run for
    > about more minutes, before turning it off……..since I know i have to
    > re-start it in less than an hour to go to my second destination….so
    > tha when i re-start it the engine should still be warm.

    > Also, in other cases, if after reaching the first destination with the
    > engine not fully hot…., rather than turn it off, i’ll just leave the
    > car and let the engine run (if it’s just a short stop over, like 5
    > minutes) and then go on to my 2nd destination.

    > I’m wondering whether i’m doing any good by this.

    Depending on where you are leaving the engine idling may be illegal. It
    is also a very poor idea since many of the insurance companies have it
    buried in the fine print that leaving the keys in the vehicle means they
    don’t have to cover it in the event of loss/theft. It is also not
    required with modern vehicles and oils.


    Steve W.
    Near Cooperstown, New York

  8. admin says:

    mac wrote:
    >"… I’m wondering whether i’m doing any good by this."

    Your Owner’s Manual will probably say you are in the severe driving
    condition catagory. As far as oil change intervals, it means follow the
    RECOMMENDED o.c.i. If I were in this situation, and using my favorite
    synthetic engine lubricant, I have the option and confidence to follow
    what it claims on the lable.

  9. admin says:

    mac wrote:
    >>You’re probably doing HARM through excessive fuel dilution into the
    >>lubricating oil.

    > Interesting….I was reading in the past few years that idling doesn’t
    > hurt the engine any more than driving does….but i think a LONG time
    > ago I used to hear that it’s not good to idle too "long" (an hour?).

    The problem isn’t idling, its idling when cold. Idling will *never*
    bring the oil up to full operating temp, even if the coolant gets there,
    and its the oil that really needs to be heated to drive out absorbed
    fuel and water vapors.

    > One slightly related (to my original question)  thing I heard last
    > year:    If your going to let you car sit parked (off) for a long time
    > (weeks??),  you should NOT ‘t drive a short distance and then turn the
    > engine off before the long parking duration….You should drive it
    > until it’s fully warmed up….supposedly the condensation in the engine
    > would remain there and cause rust if you don’t fully warm it before
    > turning it off and letting it sit…….true?

    Its not that it causes rust, its that it causes acid formation in the
    oil.  But yes, its generally true. An occasional short cold trip really
    isn’t going to do any harm because the buffers in oils can handle the
    acids just fine. But doing that sort of thing on a daily basis will
    eventually overwhelm the oil and the total base number will decline,
    meaning the oil is becoming acidic.

  10. admin says:

    I borrowed and electricity consumption meter from the public library
    and put some of the numbers I got in a file a
    http://www.ag384bn.bravehost.com/hydro.htp including the block heater on my
    car. You can find some vauge references to fuel savings using a block
    heater on the Internet but no hard data. It would be nice to have.

    My impression is that an engine idling over any time without a load on
    it will shake itself silly but an engine with a load on it won’t shake
    as much. Just an unrpoven theory of mine. My manual says not to idle
    more than 30 min.

    Here in Ottawa where winters get pretty cold remote starters are
    popular just to warm up the car so people have a nice warm car to get
    into, nothing to do with the engine, everything to do with creature
    comfort.

  11. admin says:

    Wm Watt wrote:
    > My impression is that an engine idling over any time without a load on
    > it will shake itself silly but an engine with a load on it won’t shake
    > as much.

    Uh…. no. The engine is just as balanced at idle as it is under load.

  12. admin says:

    > Define cold.
    > Cold to me is anything below 85F.  Below 50F and I don’t go outside.

             On the Canadian Prairies:
    85F = Hot day. Stay in the shade.
    50F = Might want a sweater on.
    40F = Time for the jacket.
    20F = Time to change the oil. Max 5W30, maybe 0W30.
     0F = Getting a little chilly. Might want to warm the engine for two or
    three minutes before driving or it might cough and die.
    -20F = Plug in the block heater. Put on long underwear. Wear a hat.
    -40F = Some parents keep kids at home from school. The rest of us go to
    work.
    -50F = Can’t talk outside. Your words freeze and fall to the ground,
    and in the spring everyone can hear what you said about them when those
    words melt.
    -60F = Smoke freezes in the chimney and the furnace fumes back up into
    the house. Got to climb up on the roof and poke a long stick down
    through the frozen smoke, turn the heat way up and burn the rest of it
    out.
    -70F = Can’t drive at night. The headlight beams freeze to anything
    they hit and immobilize the vehicle. Have to turn off the lights to get
    moving again.

              Dan

  13. admin says:

    Thanks for the replies.  I’ve actually never left my car running
    unattended, and i never planned to  (what i meant at the end of my
    original message was that i might let it run while stopping at a
    destination, but not leaving it alone (like more than 10 feet away from
    me).

    Actually, the only time i let it run unattended was in an long-term
    airport parking lot a few weeks ago, when I flew to Europe for one
    week, and left the car running in the parking lot for a week, because i
    heard the weather was gonna be very cold….and didn’t want to start it
    when i got back….didn’t seem to cause any problems, though gas was
    almost empty.  
    (just kidding)

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