Warming up a car

Just how important is it to let your car engine warm up? I have never done it, but I know people who let their car run for sometime before driving (and not just in cold weather). Is there a good reason that I should be doing this?


Until a mechanic comes along, I’ll throw this out. On the boats I’ve worked on, the engines are always given warm up time, until the oil temp is up to about 140 F. IIRC, the oil works best on engines under load, when it’s hot, preventing wear and fatigue to the parts of the engine. To run an engine hard with cold, thicker less viscous oil, increases the chance of longterm damage from wear and fatigue. I’ve also heard it’s good to at least wait a few minutes in your car to allow the oil to get everywhere it needs to be, before driving. When the engine is off, all the oil eventually drips back down into the pan.

In the most recent car manuals I’ve read (both Renault’s btw) it says not to let the car run on idle while it’s warming up, just to drive non-aggressively until the the engine reaches normal operating temperature.

If you are using a good quality oil, a few minutes is all that is really required. Hard acceleration and freeway driving should be avoided till the engine is up to operating temperature though.

IANAM either, but I’ve always warmed the engine up briefly, a few minutes tops, just to get the oil circulating. I’ve heard that over excessive warming tends to build up condensation in the exhaust system, leading to corroded pipes. Pure speculation though.

then you can tailgate, cut people off and drive aggressivly as you want :wink:

I’ve heard that modern cars do not need idle warm up unless it is very cold (below 0F) then only about 15 seconds. The rpms of ideling will allow waer patterns to develope - just take it slow at 1st.

Unless you’re using a single grade oil,eg,30,40 there’s no need for any warmup,other than giving the arabs (and Bush’s buds) a little more cash.

Multi-grade oil,eg,10W-30,performs like a 10 weight oil when cold ( starting) and the higher # when hot.Further the sludge (if any) in the crankcase could cause cylinder wall/ring wear sooner than normal since at lower RPM’s (idlng when cold) the oil contaminants (which settle when the engine cools) will have a smaller chance to be blown out the exhaust,than under a higher operating speed.

Like the Olds,today’s oils aren’t your granpa’s

Cartalk says it’s a bad idea for carbureted engines, but doesn’t harm modern fuel injected engines. It doesn’t say whether or not you should warm up a modern engine.

This page says:

And an environmental site advises against idling to warm up newer cars.

On a side note, turbo charged cars need to be cooled down, (and perhaps warmed up as well).

Turbochargers get extremely hot when run hard, and if you turn the car off immediately when you stop, the blades will warp as they cool without any lubrication running through them.

Letting the car idle and cool down allows the turbos to cool with oil running through them, prolonging their life.

Just took delivery of a brand new Toyota yesterday. On reading through the owner’s manual, the manufacturer was very clear that the car should not be warmed up in idle, particulalry during the running-in period. In fact, it was very clear that the car should not be run in idle for prolonged periods at anytime (in traffic jams etc).

The manual did not give any reasons for this, just that it didn’t need to be/ should not be done.

The Cartalk Guys are very clear that there’s no need to warm up any modern car unless the temps are very low. Just start the car and go, but hold off on going highway speeds for the first few minutes.

What do you mean by ‘warm up?’

My manual states to wait ten seconds. You know gas pedal in start, wait ten seconds, gas pedal in.

There was a guy with a 70’s TR7, who let it warm up fifteen minutes.

[biased opinion] The Cartalk guys advice that I have seen in the past is at times quite shady and amateur-ish. I would not want to use them as a credible “cite” unless I couldn’t avoid it.
[/biased opinion]

I live in a climate that periodically gets to -40 and even then I don’t let it “warm up” for much more than a few seconds.

Get the oil flowin’ which happens almost immediately is good enough for me.

Slight caveat here: It doesn’t hurt to let it idle for couple minutes when it is bitterly cold (<-30) as it can be very sluggish shifting otherwise as the oil is terribly thick. This can go for both auto and manual transmissions.

A couple years ago I had neibors who would warm up their car every morning by starting it, then aggressively reving the hell out of it for a couple minutes - it woke me up sometimes; I do belive that kind of “warm up” defeats the whole purpose… no wonder that car was always crapping out.