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Discussion Starter · #1 ·
just had an insp 2 service and when I collected the car I asked whether the auto box lubricant had been changed. The service guy said that it hadn't and he didn't know when it would be changed. He thought it might be a lifetime item.

Does anyone know what the schedule for this is please?

My car has covered 53k miles.

cheers
 

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Your car will probably use the ZF gearbox (5HP19).

This is filled with lifetime oil that doesn't need changed according to BMW.

However, many people think this is nonsense and believe it should be changed at around 60K depending on use.

At the same time, the filter can be changed.

The problem with this box, however, is a lot of the oil is in the torque converter. So, when the oil is drained from the sump only about 1/3 is removed. A properly equipt auto specialist will pump through and flush out all the oil but a dealer doesn't have the kit for this. Another technique is to change the oil from the sump a few times thereby replacing most of the old oil.

The method of filling the box is also a pain. Requires filling the box up so that when the gearbox hits 35 degrees C, it starts to leak from the fill point..!
 

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Discussion Starter · #3 ·
Thanks for this, it's interesting that a lot of places can't fully drain the oil. As you say it would take a couple of tries to cleanse it fully.

Having said that I'd be interested in getting this done though would leave it until around 100k or another couple of years maybe.
 

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How can you find out which auto gearbox you have? I have a 2003 model (facelift) with 67K on the clock and just want to make sure that I minimise risk of anything going wrong. Wouldn't it be safe to leave it as people who I know with autos havent really changed their auto oil and they have covered over 100K miles (or is this just luck)?
 

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Hmm, I think BMW is correct on this because this oil doesn't break down with time, nor do I think it has additives which do. Hence, the main issue is pollution of the oil, i.e. brake band and clutch disk friction material and possibly some metal shavings (sludge). Because of the way a modern tranny is lubricated and operated the amount would be tiny so that the oil and filter would probably be ripe for replacing at the time the box is worn out and need overhauling anyway. Hence, I don't see changing gearbox oil would extend the lifetime of the tranny - so in general no reason.

When I say 'in general' is it because there will be a few rare circumstances in which you could destroy the oil prematurely, e.g. if your car is flooded - don't laugh, happened to me once when my car was parked in a Dutch harbour and there was a flood while I was away - or in extremely dusty conditions. In such cases a symptom would typically be valve body problems, erratic shifting, etc, which would be picked up by the vehicle electronics and flagged.

I don't know how BMW dimension their gearboxes but I would expect a service life of at least 150k miles of normal use - and the same for the oil. Tribology has come a long way since automatic boxes started to emerge on standard cars in the beginning of the 1950s :D.
 

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In many cases, a change of oil won't change the life of the box but the lifetime oil will degrade over time. The pressure and heat in the bearings will damage the oil but BMW have decided that in most cases the oil will last long enough. With more energetic use, the wear rate will be higher.

If a ZF box like the 5HP19 gets water inside, ZF tell you it is beyond repair. This is because the clutchs absorb water and rust from the inside over time. At the very least, all the clutchs need replaced and the box rebuilt.
 

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In many cases, a change of oil won't change the life of the box but the lifetime oil will degrade over time. The pressure and heat in the bearings will damage the oil but BMW have decided that in most cases the oil will last long enough. With more energetic use, the wear rate will be higher.
The temperature cycling lies in the range from ambient temperature up to max around 80C, not enough to cause oxidation of any significance.

Of course the wear rate will be higher if you hammer your tranny but again the service life of the oil will not be the determining factor - the thickness of the clutch linings probably will :D
 
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