[KevM2]

I’ve watched videos showing the differential fluid change at break-in service and the fluid is massively dirty with metal shavings on M-differentials…. The procedure is simply a drain and fill… I’m wondering, given how dirty this fluid is, if it wouldn’t be bettter to do a flush with a double drain and fill…. I’ve heard some people get an M-differential “hum” which essentially needs a diff replacement and now I’m wondering if it could at all be from how dirty these get… I read somewhere that it’s recommended to do a drain on these on every 5th oil change… I’ll be taking mine in for the break-in diff fluid change next week and I’m very likely to do a drain and fill myself just before taking her in. Any thoughts on this?

[M2 CCO]

Probably more of a preference thing but since you are so close the break in service date I would just let them perform the first drain and fill and then come back after them for the DIY drain and fill. Not sure it matters for any warranty concerns if BMW does the first drain and fill or not.

[RockCrusher]

Originally Posted by KevM2

I’ve watched videos showing the differential fluid change at break-in service and the fluid is massively dirty with metal shavings on M-differentials…. The procedure is simply a drain and fill… I’m wondering, given how dirty this fluid is, if it wouldn’t be bettter to do a flush with a double drain and fill…. I’ve heard some people get an M-differential “hum” which essentially needs a diff replacement and now I’m wondering if it could at all be from how dirty these get… I read somewhere that it’s recommended to do a drain on these on every 5th oil change… I’ll be taking mine in for the break-in diff fluid change next week and I’m very likely to do a drain and fill myself just before taking her in. Any thoughts on this?

A bit OCD but I'm with M2iast: Couldn't hurt.

Well, provided you refill the diff with the proper fluid and the correct amount of fluid (and any additives BMW might call for) and be sure the drain plug and refill plug are properly torqued.

How many miles to do this before you take the car in for a scheduled engine oil and diff break in fluid service is up to you.

Think you should strive to drive the car enough to get the diff fluid up to temperature.

Tech will probably be surprised to see the fluid condition when he opens the drain plug...

[KevM2]

Originally Posted by RockCrusher

A bit OCD but I'm with M2iast: Couldn't hurt.

Well, provided you refill the diff with the proper fluid and the correct amount of fluid (and any additives BMW might call for) and be sure the drain plug and refill plug are properly torqued.

How many miles to do this before you take the car in for a scheduled engine oil and diff break in fluid service is up to you.

Think you should strive to drive the car enough to get the diff fluid up to temperature.

Tech will probably be surprised to see the fluid condition when he opens the drain plug...

I decided to have the dealer do the first diff fluid change yesterday and I will repeat it myself in a few days just to satisfy my curiosity as to how dirty it might still be. Thanks for the advice. I got brand new plugs which apprently bmw calls for which not many people including my dealership changes. The torque spec was a little controversial with many stating a value of 60NM but the correct value is 45NM.

[c1pher]

I guess it's more expensive to properly mill the gears/teeth than to get the diff fluid changed out in short order. Or maybe there is some sort of fitted mating that occurs between the teeth as you break the car in that is unique for each vehicle....I dunno.

[KevM2]

Originally Posted by c1pher

I guess it's more expensive to properly mill the gears/teeth than to get the diff fluid changed out in short order. Or maybe there is some sort of fitted mating that occurs between the teeth as you break the car in that is unique for each vehicle....I dunno.

I also just learned the bmw diff fluid comes with an expiry date stamped on the bottle that’s about 2 years from production. Just something I never noticed or paid attention to with other non bmw diff fluids…. Makes me wonder if it has a shelf life that’s only 2 years then does this mean it should also be drained out every 2 years?

[aerobod]

Originally Posted by c1pher

I guess it's more expensive to properly mill the gears/teeth than to get the diff fluid changed out in short order. Or maybe there is some sort of fitted mating that occurs between the teeth as you break the car in that is unique for each vehicle....I dunno.

It is actually the LSD friction plates bedding in that creates most of the oil contamination, there will be very little from the gears.

[RockCrusher]

Originally Posted by KevM2

I decided to have the dealer do the first diff fluid change yesterday and I will repeat it myself in a few days just to satisfy my curiosity as to how dirty it might still be. Thanks for the advice. I got brand new plugs which apprently bmw calls for which not many people including my dealership changes. The torque spec was a little controversial with many stating a value of 60NM but the correct value is 45NM.

Interesting to learn BMW calls for replacing the plugs.

I recall with my Porsche cars the engine oil drain plug required a sealing ring, not a crush washer. And this was not to be reused.

The reason was the sealing ring -- made of IIRC a silicon bronze alloy and very hard and very flat and very smooth -- was the sacrificial item in the drain plug/engine oil pan (or in the case of my Turbo oil tank) partnership. Upon removing the drain plug the sealing ring would have a slight but noticeable depression from the drain plug on the side the drain plug was tightened against. Re use of this ring would have that marred the drain plug surface or the sealing surface of the oil pan/oil tank.

This over time would cause the very smooth/flat surface of the drain plug and oil pan/tank to become damaged. Techs told me the result was after a while the plug/oil sump sealing -- even if the old ring was replaced with a new sealing ring -- was compromised and there was a bit of oil wetness around that area. I always replaced the sealing ring. My Boxster's oil sump/drain plug area was dry even at 317K miles and with oil changes every 5K miles after approx. 63 oil changes. The Turbo had 161K miles and thus had 32 oil changes. Its oil drain plug and where it plugged the tank was dry too.

Not only did the oil sump not leak the oil drain plug was oil tight too. In spite of being aluminum I only had to buy one oil drain plug the whole time I owned the car. I took the car to a oil change place -- the dealer was booked -- and supplied the oil, filter, filter o-ring, and oil drain plug sealing ring. But what happened was the 8mm Allen tool bit hole in the drain plug was so precisely sized it took a bit extra attention to ensure the tool bit was fully inserted into the hole. The oil change tech didn't do this and while he was able to remove the drain plug and tighten it again (probably using the 50 ft lbs of torque he said his employer required rather than the approx. 37 ft lbs Porsche called for and which I requested he use) when I had the car in to a dealer for its next oil change -- just a week later after putting 5K miles on the car on a road trip -- the tech found the tool bit hole buggered. He managed to get the bit to hold and was able to loosen/remove the damaged drain plug. He had a spare which he used. When he told me what he had found I ordered two new drain plugs at the parts counter. A few days later when they arrived I gave one to tech to replace the one he used in my car and put the spare in the glove box to have just in case. When I sold the car that new drain plug was still in the glove box.

[M_Power Rob]

Originally Posted by RockCrusher

Interesting to learn BMW calls for replacing the plugs.

I recall with my Porsche cars the engine oil drain plug required a sealing ring, not a crush washer. And this was not to be reused.

The reason was the sealing ring -- made of IIRC a silicon bronze alloy and very hard and very flat and very smooth -- was the sacrificial item in the drain plug/engine oil pan (or in the case of my Turbo oil tank) partnership. Upon removing the drain plug the sealing ring would have a slight but noticeable depression from the drain plug on the side the drain plug was tightened against. Re use of this ring would have that marred the drain plug surface or the sealing surface of the oil pan/oil tank.

This over time would cause the very smooth/flat surface of the drain plug and oil pan/tank to become damaged. Techs told me the result was after a while the plug/oil sump sealing -- even if the old ring was replaced with a new sealing ring -- was compromised and there was a bit of oil wetness around that area. I always replaced the sealing ring. My Boxster's oil sump/drain plug area was dry even at 317K miles and with oil changes every 5K miles after approx. 63 oil changes. The Turbo had 161K miles and thus had 32 oil changes. Its oil drain plug and where it plugged the tank was dry too.

Not only did the oil sump not leak the oil drain plug was oil tight too. In spite of being aluminum I only had to buy one oil drain plug the whole time I owned the car. I took the car to a oil change place -- the dealer was booked -- and supplied the oil, filter, filter o-ring, and oil drain plug sealing ring. But what happened was the 8mm Allen tool bit hole in the drain plug was so precisely sized it took a bit extra attention to ensure the tool bit was fully inserted into the hole. The oil change tech didn't do this and while he was able to remove the drain plug and tighten it again (probably using the 50 ft lbs of torque he said his employer required rather than the approx. 37 ft lbs Porsche called for and which I requested he use) when I had the car in to a dealer for its next oil change -- just a week later after putting 5K miles on the car on a road trip -- the tech found the tool bit hole buggered. He managed to get the bit to hold and was able to loosen/remove the damaged drain plug. He had a spare which he used. When he told me what he had found I ordered two new drain plugs at the parts counter. A few days later when they arrived I gave one to tech to replace the one he used in my car and put the spare in the glove box to have just in case. When I sold the car that new drain plug was still in the glove box.

I believe Audi requires replacing the plug (and o ring) when servicing their transmissions.

[KevM2]

Originally Posted by RockCrusher

Interesting to learn BMW calls for replacing the plugs.

I recall with my Porsche cars the engine oil drain plug required a sealing ring, not a crush washer. And this was not to be reused.

The reason was the sealing ring — made of IIRC a silicon bronze alloy and very hard and very flat and very smooth — was the sacrificial item in the drain plug/engine oil pan (or in the case of my Turbo oil tank) partnership. Upon removing the drain plug the sealing ring would have a slight but noticeable depression from the drain plug on the side the drain plug was tightened against. Re use of this ring would have that marred the drain plug surface or the sealing surface of the oil pan/oil tank.

This over time would cause the very smooth/flat surface of the drain plug and oil pan/tank to become damaged. Techs told me the result was after a while the plug/oil sump sealing — even if the old ring was replaced with a new sealing ring — was compromised and there was a bit of oil wetness around that area. I always replaced the sealing ring. My Boxster's oil sump/drain plug area was dry even at 317K miles and with oil changes every 5K miles after approx. 63 oil changes. The Turbo had 161K miles and thus had 32 oil changes. Its oil drain plug and where it plugged the tank was dry too.

Not only did the oil sump not leak the oil drain plug was oil tight too. In spite of being aluminum I only had to buy one oil drain plug the whole time I owned the car. I took the car to a oil change place — the dealer was booked — and supplied the oil, filter, filter o-ring, and oil drain plug [...]

Yeah these bmw plugs also have a built in sealing rubber (green colour) and I think for that reason they call for a new plug. I’ve seen at least a couple members here post about a bit if a leak after they went in for the break in service. I have a feeling it might be from reuse of the plug and/or perhaps wrong torque spec being used… but they all said tightening the plug a little more seemed to have stopped the leak…

[EnlightenedOne]

Pardon my ignorance... but what is "break in service"? Is this only something on the M2?

[KevM2]

Originally Posted by EnlightenedOne

Pardon my ignorance... but what is "break in service"? Is this only something on the M2?

As far as I know it’s for all M cars where they change out the “break-in” engine oil and the rear differential fluid at 1200 miles and do a quick inspection and that’s it… then you are allowed to rev the engine as high as you like and not void any warranties