[dzenno]

all i know is that the standard 75w90 gear oil has the friction modifiers that are required for clutch type diffs and the gear type limited slip differential manufacturers mandate to stay away from them and in the case of Redline they recommend the NS..they also say either stock oil OR 75w90NS which to me logically means the stock oil has no friction modifiers either

[AlanAZ]

Originally Posted by dzenno

all i know is that the standard 75w90 gear oil has the friction modifiers that are required for clutch type diffs and the gear type limited slip differential manufacturers mandate to stay away from them and in the case of Redline they recommend the NS..they also say either stock oil OR 75w90NS which to me logically means the stock oil has no friction modifiers either

That's all probably true, but you appear to be arguing that we all have gear type limited slip diffs., which we don't.

I have no doubt that if NS was the better choice for an OEM diff, the RedLine website would list it as such. I and many others have run the standard RedLine gear oil in our BMW diffs for many years without ruining them.

[tibra1]

I have an OS Giken ..its a clutch type dif and I am using their gear oil which is 80w-250..clutch type diffs are notorious for chatter so the gear oil u use is critical..

My understanding is the OP has a stock diff anyways..so a redline 75-90 would be more than sufficient.

[dbjb]

Originally Posted by dzenno

.... Redline they recommend the NS..they also say either stock oil OR 75w90NS which to me logically means the stock oil has no friction modifiers either

I believe the same.

However, since the OP is using a stock diff, I see no reason not to use OE fluid as well.

[queensfield]

Originally Posted by Glim

I use a mitivac mv7201

http://www.mityvac.com/pages/products_fee.asp#07201

Have you used the cap adapters on mityvac for the cooling fluid extraction?
Link below is meant for BMW 3 series 2006.
http://www.mityvac.com/pages/search_...d=36&year=2006

[Glim]

Originally Posted by queensfield

Have you used the cap adapters on mityvac for the cooling fluid extraction?
Link below is meant for BMW 3 series 2006.
http://www.mityvac.com/pages/search_...d=36&year=2006

I did not pick up any cap adapters, I use it to drain the resevoir and then followed the coolant DIY.

I wonder if these replace the drain plug at the bottom of the rad and the reservoir filler cap?

[Express]

Originally Posted by tibra1

Yea but I dont own an automotive dealership...the reason BMW put no drain plug is b/c they are advocating that lifetime fluid bullshit for the diff//

100% false. does that mean jeep didn't put a drain plug on my TJ because they are trying to imply lifetime fill??

[JunkStory]

No need to do diff oil at 30k miles. I'm at ~50k miles, and I just swapped my diff fill plug with a magnetic one from Gold Plug, and inspected the oil. It still looks and smells brand new. The 328 also handles less torque so the oil should last even longer.

[AlanAZ]

Mike Miller, BMW CCA Roundel Magazine Technical Editor, and author of the "BMW Old School Maintenance Schedule", provides good information on diff. maintenance. Since it's copyrighted, I can't post it here, but Google it and you'll find it.

Notably, he writes (I'm paraphrasing):

... E90 non-M diffs too new for longevity predictions, but not looking good... diffs have gotten smaller, pinion gear now very small, oil capacity reduced, and strong tapered roller bearings were changed to regular ball bearings... diff. rebuilder thinks oil changes is the best bet for maintenance, but is also suspicious of the plastic bearing cage.