Which Differential Fluid

[Georj]

I just bought a 2008 128i with 82K miles. I am looking to change the differential fluid. I have seen two conflicting recommendations. Some say 75W90 and others suggest 75W140. Which one is right one. I have a 6 speed manual transmission.

[Olgeezer1]

You want 75W90. I'm using Redline but any quality gear oil will do. No drain plug so you'll have to use some kind of suction device of about 3/8" to get down in there as far as you can. Every 50k. miles is a good idea.

[MightyMouseTech]

I would do 75/90 unless you are doing a lot of track days or pushing serious torque, like 500. Redline makes good stuff and is easy to get.

[Georj]

Thank you guys

[fast1eddy]

Here's what I'd recommend.

[Gray_Panther]

Originally Posted by fast1eddy

Here's what I'd recommend.

I have the same setup! Makes for a nice morning job.

[jdt10768]

what model/brand pump is that please? I need to buy one

[Georj]

Originally Posted by fast1eddy

Here's what I'd recommend.

Thank you for a very concise reply. A picture is worth 1000 words

I am curious why are you using Redline ATF instead of Redline MTL 75W80.

Do you have automatic transmission?

[fast1eddy]

I have a manual transmission but that's what Redline recommends.

[fast1eddy]

Originally Posted by jdt10768

what model/brand pump is that please? I need to buy one

Just a basic no name pump from Princess Auto, Canada's equivalent to Harbor Freight. I replaced the crappy hose it came with. Works perfectly.

[krhodes1]

Originally Posted by fast1eddy

I have a manual transmission but that's what Redline recommends.

In a cold climate probably the way to go.

Down here in God's Waiting Room, FL where the natives put on parkas at 60F (I am not kidding), I use MTL and MUCH prefer it to D6 in the heat. Or the BMW special unicorn tears original fluid.

[Georj]

I just did the differential fluid change. Based on the recommendation here, I used Redline 75W90. On draining the old oil, only less than 1/2 quart came out. But I was able to put in 1.5 quart. So it was low by 1 quart. I did not see any leaks, just the normal seepage. I am wonder where did 1 qt of differential fluid went.

[krhodes1]

Originally Posted by Georj

I just did the differential fluid change. Based on the recommendation here, I used Redline 75W90. On draining the old oil, only less than 1/2 quart came out. But I was able to put in 1.5 quart. So it was low by 1 quart. I did not see any leaks, just the normal seepage. I am wonder where did 1 qt of differential fluid went.

That's peculiar. Was the car dead level when you filled it? If you had it up on ramps in the back or something nose down you probably WAY overfilled it.

How did you drain it too? I used a vacuum bottle like you would use to drain oil from the dipstick tube with a couple feet of 1/8" hard plastic hose on the end, and you have to stick it waaay in there to get it all. I got probably 95% of whatever the official fill amount is out is - 1.8L or some such (it's been a few months)? Same amount went back in.

[Georj]

I did the work with my Indy at his shop. We had the car hoisted on the lift in his shop. So I believe the car was not sloping. We used a hand pump to drain the old fluid. We made sure all the fluid was out by checking with a bent plastic tie (makeshift dip stick). Then I was surprised that we pumped in almost 1.5 qt of new fluid when it started to overflow. I was told that the total capacity is 1.1L

[krhodes1]

Originally Posted by Georj

I did the work with my Indy at his shop. We had the car hoisted on the lift in his shop. So I believe the car was not sloping. We used a hand pump to drain the old fluid. We made sure all the fluid was out by checking with a bent plastic tie (makeshift dip stick). Then I was surprised that we pumped in almost 1.5 qt of new fluid when it started to overflow. I was told that the total capacity is 1.1L

Sounds like you did it right. Odd that you have no sign of leakage, but it sure sounds like you were quite low of oil.

Like I said, pretty sure I got rather more than 1L out of and into mine - def more than 1L, def less than 2L. I'm sure rather more than 1.1L.

Keep an eye on it, and check the level occasionally. Hope it's just a fluky thing!

[Georj]

Yes, the low volume of old oil coming out is my concern. The Indy said that there is a relief valve on the top of the differential and sometimes the oil gets too hot and escapes. He is not a BMW specialist, but very experienced. I am not sure if what he is saying makes sense. May be some members here more familiar with the differential can comment