let your X5 really warm up

[lowlows18]

Originally Posted by audiophool

Nope. Start it and drive away gently - the engine warms up best with a light to moderate load. There's no reason to idle for more than a few seconds other than if you need to scrape your windows or brush off some snow. Keeping a light foot until the engine is warmed up makes a lot more sense.

sounds right to me

[rolfi]

Originally Posted by rb0135

I agree (and so do mechanics) even with the Diesels. Start it up before you have done your seatbelt, etc. Get yourself comfy, do the seatbelt up, usual pre-flight checks then go. Don't speed/race the engine, drive normally. And, with the diesels especially, don't over rev the turbo until it is thoroughly warmed up.

In cold weather, if I waited for the diesel to warm up idling, I would be waiting 1/2 a day...

All X5 diesels I have seen, has the Webasto heater. Maybe it's only the Euro ones? It starts when the engine starts, and warms the engine up in minutes. In the winter, I have my webasto set to start on its own 30 minutes before I leave for work (Aux. heating), so I have some heat in both engine and cabin before starting up and driving off.


I would be careful starting the car dead cold and letting it warm up on idle every day before driving off. The lubrication is not ideal on idle, and especially when the oil is thick and cold. It may cause premature wear due to poor lubrication. Drive off as soon as possible to get the oil temp up, and some heat in the engine.

When the engine is cold there is also more fuel injected just to keep it running, and there is a possibility of fuel slipping past the piston rings. The lambda sensors are disconnected when cold, so the fuel injection system won't compensate and lean off the air/fuel ratio under a certain temperature. That means more unburnt/badly burnt fuel will pass through the system, and might clog the cats over time. Cold idling may also leave soot on the spark plugs because of this.

When I worked as a mechanic and, I could often tell which cars had been idling during warmup. The engine oil smelled a lot more of fuel on those, and I usually asked the owners to see if my assumptions were correct. In almost every single case, I was right.

When driving off when the engine is cold, you will speed up the heating process. The cats will warm up quicker, the lambda will start working quicker, you get the oil temp up and viscosity down (the oil becomes thinner), the increased flow speed in the cylinders will blow past a lot of the soot which would otherwise stick to the spark plugs, and the increased flow speed through the whole system will be beneficial to everything that may suffer from the cold idling.
Be gentle when driving before the engine is warm. No flooring the pedal or high engine speeds. Keeping rpms under 3000 is usually a good tip.

The Owner's Manual also states:
Do not allow the engine to warm up by leaving it running while the vehicle remains stationary. Instead, begin to drive immediately at a moderate engine speed.

[tmv]

^Yup. Stated right there in the manual. I'll give it about 10-15 secs.

[motordavid]

What JCL wrote and the same as what the manual sez...
gasoline engines are not diesels from the '80s, or a farm tractor fired up in January.

Obviously, one needs to avoid driving out of driveway and nailing it on an entrance ramp, in the first 30 seconds, but common sense and no need to let it idle/warm up, are the way.

[upallnight]

Like I said I wait for high idle to drop so that I don't need to ride the brakes when I'm driving in traffic.

[racingbmwm3]

and ideally, wait for all the orange lights to go out AND oil temp at least 160 before going above 4000rpms. (iS vehicles)

[davintosh]

Originally Posted by upallnight

Like I said I wait for high idle to drop so that I don't need to ride the brakes when I'm driving in traffic.

How high is your idle? If it's high enough that you have to ride the brakes, that doesn't sound right. Mine -- 3.0 with a manual -- normally idles at ~750rpm, and maybe 1000 when cold. I can't imagine the V8s would be much different from that.

[racingbmwm3]

Our 4.6 has a cold idle around 800 I think? then drops to 550-600?
We don't have any traffic around here, and I haven't driven the X in Seattle traffic often enough to notice if I'm riding the brakes or not.

[upallnight]

Originally Posted by davintosh

How high is your idle? If it's high enough that you have to ride the brakes, that doesn't sound right. Mine -- 3.0 with a manual -- normally idles at ~750rpm, and maybe 1000 when cold. I can't imagine the V8s would be much different from that.

You have a stick which is completely different from an auto. High idle when the engine is cold is somewhere between 900 and 1000 rpm. If you put the trans in D the idle is high enough that you need to keep the brake on it to prevent the truck from taking off.

[Doru]

I also let it idle no more than 30-45 secs or so, usually until the rpm's start to drop. This usually coincides with the SAP turning off. Just let the oil start to flow.
Also, the ATF does not get warmed up by idling. It warms up from the engine, so driving gently until the temp needle starts creeping past 10 o'clock is the best way of warming the car up (in my books).