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.

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
------------------------------------------------------------------------
MishaA's Profile: http://www.automotiveforums.com/vbul...?userid=469060
View this thread: http://www.automotiveforums.com/vbul...d.php?t=643704

http://www.automotiveforums.com

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.

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" > wrote in message
oups.com...
> 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.
>

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.

>
> 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?

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.

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

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.

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.