I let my car warm up for about 5 minutes. I drive such a short distance (1 mile each way) that the engine doesn't have a chance to warm up. I get more miles to the tank when I let my car idle longer. The only time I dont warm it up as much is if I know i'm going to be driving far.

 

My old M5 manual states that the oil temp should be 140 degrees or above before exceeding 4000 rpms or putting the engine under heavy load. As it has an oil temperature gauge I can tell you it takes much, much longer to see any increase in oil temperature as compared to water temp. Depending on the terrain (hills vs. flat) it can take 5-10 miles of driving. I can also say from experience that it takes forever to get it there if it is just idling. I can't count how many times I have passed up a challenge because my engine is not to operating temperature yet.

Most questions like this are just a matter of common sense. I do wonder if sitting at idle is ideal for oil circulation given the low rpm's.

For those leasing, have at it from start up.

 

Did yours have the variable red line? I remember seeing that in one of the magazines - red line would change based on oil temperature. And yes, oil takes quite a bit longer than coolant to get to full temperature.

Idling is terrible for oil circulation. Everything is at absolute minimum effectiveness. Just enough to keep disaster at bay, which is why it is so cruel to lug an engine - not enough oil pressure to keep the rod bearings from making metal to metal contact with the crank!

 

I park outside. During winter, or days like today when the windows are frosty, I let it warm up enough that the defroster does its job.

 

I agree. Which is why I switched to (2) quarts of 0w-20 mixed with (3) quarts of 5w-30 of synthetic mobil 1 for my GS400. I just dont have the distance needed to warm up the oil so I switched to a mixture of lighter oil to help.

 

One of the things not good for cars is a lot of start ups and a short drive.

Let me ask a question. How many guys here have driven a car until it starts burning oil and needs a rebuild? Thought so. However, I guess putting stress on parts when cold could result in what happened to me as set forth below.

I rebuilt my M5 at 161,000 due to a broken valve spring. When they had the head off there was some detonation damage so I decided what the heck it is only $13k. It was not using an unusual amount of oil and there were hash marks still on the cylinder walls.

 

I can't get around driving short distance. I should use a bike instead, but its not convenient. lol.

 

I can't think of a worse combination ... long idle AND short drive. The long idle makes it even more important that you have a long drive. What else is going to burn off the contaminants in your oil that are introduced by the long idle?

 

Very short drive with no warm up yields me 8mpg. a 5 minutes idle driving the same distance gets me 13-14mpg. My car has 128k miles on it already so i'm not too worried if my old car with almost 200k beater can take it. It's bad for the engine, I know, but bad enough that the car can't be driveable by the time it hits 200k? I'll take my chances to gain 6mpg.

 

as long as it takes for me to turn on the lights and my iPod

 

Does this takes in consideration the 0 mpg during the 5 minutes warm up?

 

I calculated the miles I get per tank in both cases. If anything, idling for a longer time "should" waste more gas, but in my situation, I get more miles to the tank if I let my car idle for 5 minutes

 

Now that were on this subject I got a question: I've noticed that my car makes a small humming noise when I drive the car in the morning. This sound gets lower and lower and goes away after driving for about 2-3 minutes. After parking my car at work and turning it on 8 hours later it does it for a little while, but if I just leave it parked for a couple of hours it doesn't do it. I don't know how else to explain this sound, just a faint humming sound.


Anyone else noticed this or have an answer ???

 

car is parked in garage. start the engine, put on seatbelt, check nav, stereo, and then go about 30 seconds later. Easy on the pedal the first minute in the cold months. Lead foot in Summer.

 

more of a whining sound than a hum..its the direct injectors working overtime.