warming up your car

"giganut" > wrote in message
...
> Hi
>
> How important/necessary is it to warm up your car before driving off ? i
> hear many contradictory opinions about this - some say you need to warm up
> for a couple of minutes to let the lubricant get all around the engine,
some
> say 30 secs, and a few say don't bother ?
>
> What is the deal for fuel injected vehicles ?

I b elieve a thorough warmup is less important than it used to be. In the
old
days, engine clearances and materials were less conducive to long engine
life than they are now.

Carburetors often tended to run very rich during cold choke conditions, and
the engines would stumble and protest until well warmed. (Sometimes
afterward
too.) They could be dangerously unresponsive under today's driving
conditions.

Oil was often diluted by raw gasoline, which really didn't help anything
either.

With modern engines, fuel injection makes the engine run smoother under
a wider range of conditions--- and when you have developed oil pressure
(usually within a few seconds after you start up), you are good to go.

In cold weather, your heater will take a while to warm you up, but your car
will
get along just fine.

In article >, says...

>Now, my understanding is that driving gently (keeping rpms and bmep
>down) is better, and keeps from pounding bearings, till temps come up.

That's what I do.
----------------
Alex

Don Stauffer wrote:
> Alex Rodriguez wrote:
>
>> In article >,
>> says...
>>
>>
>>> Hi
>>> How important/necessary is it to warm up your car before driving off ?
>>
>>
>>
>> No. In fact is bad for your car.
>>
>>> hear many contradictory opinions about this - some say you need to
>>> warm up for a couple of minutes to let the lubricant get all around
>>> the engine, some say 30 secs, and a few say don't bother ?
>>
>>
>>
>> Minutes? Oil gets circulated in seconds, not minutes.
>>
>>> What is the deal for fuel injected vehicles ?
>>
>>
>>
>> Makes no difference. -----------------
>> Alex
>>
>
> I was always under the belief that warmup was primarily to warm manifold
> up to get better drivability (with carbed cars) and to allow expansion
> of clearances to more normal values, to cut down on fuel into crankcase
> and to keep from beating bearings with excessive clearances. That took
> a bit longer than circulating oil.
>
> Now, my understanding is that driving gently (keeping rpms and bmep
> down) is better, and keeps from pounding bearings, till temps come up.

I'd basically agree, except that its not so much the bearings that
you're protecting. Running a cold engine gently is most important for
the cylinder bores, because piston-to-wall clearance is the single
engine parameter that changes *most* from a stone-cold engine to normal
operating temperature. Bearing clearances don't change nearly as much.

John_H wrote:
> giganut wrote:
> >
> >How important/necessary is it to warm up your car before driving off ? i
> >hear many contradictory opinions about this - some say you need to warm up
> >for a couple of minutes to let the lubricant get all around the engine, some
> >say 30 secs, and a few say don't bother ?
>
> Drive off as soon as the engine runs smoothly, but go gently with the
> gas pedal until it reaches normal operating temperature. The
> corrosive by-products of combustion and water vapor are what do the
> most damage so the quicker it warms up the better. Avoid prolonged
> idling like the plague while it's still cold -- normal engine speed
> will also throw a lot more oil at the cylinder bores.

I've done some reading that suggests that ZDDP antiwear additives
have a certain activation temperature. Getting the oil up to temps
faster should speed up the process. Of course there's probably
a point where you're doing more harm by stressing the lubrication
by (let's say) revving the engine before the oil has reached its ideal
temps.

I don't know about a "standard" or if there is one, but I turn the key
on, let the pump

feed the injectors, start the engine and wait for all the test lamps to
go out, then

drive off at a slow rate of speed and continue on slowly until it is
necessary to speed up.

I prefer not to let the engine - just idle - for the hell of it.

There probably isn't much likely damage - unless one is tempted to start
and gun / rev the engine unnecessarily, I think.

mho
vfe