[Carjack]

Have been driving the 320D & 320i with auto g/box very happily for some 6 years now, and when standing at traffic lights have nearly always selected 'N' neutral.
I've done this because I read somewhere, a long time ago, that's it best to do this rather than stay in 'D' drive, to save wear & tear on the auto gearbox.
But just recently I read a letter in the BMW Car Club Mag, that for some BMW models, you should not leave the car in 'N' neutral, at say traffic lights.
Also, on a website it states that you should not leave the car in 'P' park for any length of time because it can overheat the auto box. i.e. when waiting for the Wife whilst in the hairdressers, in the winter with the engine running to keep warm.
Is this true & factual? i.e. Can't use 'N' or 'P' for longish periods on the 320D?
Would appreicate your opinion as I would like to get it right!
The BMW Manual does not seem to have any say on the matter.

[xenon]

I wouldn't worry. I suspect that you will actually cause marginally more wear & tear by selecting N at traffic lights, say.

If you leave the car in D, holding it on the brakes, then the torque converter does all the slipping and that's only a fluid coupling, after all. When you release the brakes the car moves off and nothing has significantly changed in the 'box.

If you continually take it in and out of drive then you the take-up "clunk" as you make the 'box live could wear bearings more.

Either way, I think it's insignificant and I see no problem at all idling in P.

[SO8]

I was taught to leave it in drive snd hold on footbrake if for a few seconds or handbrake for longer so as not to blind the poor person behind.

[seanblee]

Originally Posted by xenon

I wouldn't worry. I suspect that you will actually cause marginally more wear & tear by selecting N at traffic lights, say.

If you leave the car in D, holding it on the brakes, then the torque converter does all the slipping and that's only a fluid coupling, after all. When you release the brakes the car moves off and nothing has significantly changed in the 'box.

If you continually take it in and out of drive then you the take-up "clunk" as you make the 'box live could wear bearings more.

Either way, I think it's insignificant and I see no problem at all idling in P.

To add to that, with the box in P, the torque converter is slipping, whereas with it in N it isn't as the input shaft is effectively freewheeling. I can imagine that sustained periods in P (i.e. tens of minutes) could heat the transmission fluid up as the coupling is slipping, but it certainly won't do it any harm at traffic lights or similar.

[Carjack]

Many thanks for your comments! I'll continue to use 'N' whilst at traffic lights etc but perhaps not 'P' for any length of time, like waiting for the Wife. Might be best to wait in a cafe!
Cheers!