[jackliu0527]

I want to drain and replace my rear differential fluid on my BMW 650 XDrive, from my research BMW uses Hypoid Axle Oil G1 (BOT448) P/N: 83 22 2 295 532 which is a 75W85 GL-4 oil, I want to try out the Redline 75W85 oil, however, it is a GL-5 oil, even tho on the redline website it says it is compatible with the BMW 75W85 GL-4 oil even included the BMW part number, from more research online, some say that one should not be using GL-5 oil in GL-4 car because it has sulfur which could cause wear, experts please do chime in. As well is Redline oil a superior product compared to BMW gear oil? or are there other suggestions and why?

[HotSpicyChicken90]

BMW is very specific about their fluids.

Gimme your VIN, I can check for you

[Sylverlee]

I used this https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 GL-4.

[Unspec]

Originally Posted by Sylverlee

I used this https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 GL-4.

The Redline MT-85 is GL-4, but the PDS specifically says "not intended for use with hypoid gears".

[Sylverlee]

Originally Posted by Unspec

The Redline MT-85 is GL-4, but the PDS specifically says "not intended for use with hypoid gears".

What did you use?

[Sylverlee]

This was from Redline

"The back of mt85 oil says this (and isn't my differential "hypoid"?): "Not designed for hypoid differentials."

The rep replied:

"The note on our GL-4 products is referring to use in a high offset hypoid differential, your differential doesn't use a high offset ring and pinion, a GL-4 is suitable. In your differential BMW is calling for a GL-4 75W85 gear oil, the MT-85 would be a suitable replacement."

[Unspec]

Originally Posted by Sylverlee

This was from Redline

"The back of mt85 oil says this (and isn't my differential "hypoid"?): "Not designed for hypoid differentials."

The rep replied:

"The note on our GL-4 products is referring to use in a high offset hypoid differential, your differential doesn't use a high offset ring and pinion, a GL-4 is suitable. In your differential BMW is calling for a GL-4 75W85 gear oil, the MT-85 would be a suitable replacement."

Interesting that they didn't put that in the PDS, feel like that's a pretty big distinction.

I used their 75-85 GL-5. Might swap out for the GL-4 though now that I know it's fine to use. Still kind of wondering why the front diff uses a GL-5 but the rear uses a GL-4.

[Surly73]

When I was looking at everything for my 2011 535i X-Drive, I found that the rear didn't really call for anything special. Good old SAF-XO was on the list, which is pretty much any 75W90 GL5 (my choices over the years have been Redline 75W90 and Amsoil SVG). I believe that Synthetik OSP and possibly G1 were options, but SAF-XO is on the list.

The front diff was another story, with specs rigidly changing for 7/2011+ build dates even though the diff didn't change part# (reportedly an emissions thing, not a lubrication thing). Anyways - the front diff is all over the map and the most likely to be best application for my vehicle VIN was G2, which cost a pretty penny. The front diffs are built and packaged differently than the rears, for sure.

Take a look at https://www.newtis.info/tisv2/a/en/f...ide/1VnczONFlo

I like TIS documents like this as opposed to ETK (parts system) fluid specifications some times. ETK is often telling you what the car may have come with from the factory, TIS is just telling you what's OK at the time of publication. Interesting to look at anyways. I see there that they say G1 after 7/2011 under "all other vehicles". This reeks to me like an emissions or regulatory thing. You can't tell me that "all other BMWs" not specifically listed there changed differential build specs all on July 1/2011.

Bottom line, you're probably OK with an SAF-XO substitute, but I totally understand if you wished to follow the spec and go with G1, but it'll cost you.