Diff fluid

[rsutoratosu]

Gotta do my diff soon, prob next weekend. I have a bottle open from 2 years ago, if it stays in the bottle, does it degrade or I can still use it ? its redline 75w90 gear oil

[GuidoK]

You can still use it

[itdnwiwbp]

I've always heard that as long as the bottle is sealed it should be ok but I'll be interested to hear if anyone has any other information.

[rsutoratosu]

I found some people wrote to redline, they say no shelf life, suitable for use and provide full performance

[Westersund]

That might be a way for Redline to swear themselves free if someone use "old" Redline oil, then we have the profit side of things.

[pokeybritches]

The main reason for shelf life is moisture getting into the oil.

[rsutoratosu]

need someone with more chemistry background in this..

if you open a bottle and use x amount, close it, throw it in storage for 2 years, does moisture get in ?

i figure plastic bottle is non porous, so nothing get in or out.. but who knows.. water molecules might some how find its way in

[dc_wright]

Oils (motor oil, tranny fluid, diff fluid, etc.) and greases are generally hydrophobic which means they repel water. It's brake fluid which is hygroscopic (attracts and holds water) that you have to worry about storage after breaking the factory container seal.

[pokeybritches]

Originally Posted by dc_wright

Oils (motor oil, tranny fluid, diff fluid, etc.) and greases are generally hydrophobic which means they repel water. It's brake fluid which is hygroscopic (attracts and holds water) that you have to worry about storage after breaking the factory container seal.

Yes, but condensation can react with the additives.

[Westersund]

Storing the container in a room with constant temperature, moisture will be no problem.

[GuidoK]

As long as the lid has been on, there is no real moisture, only the moisture that was in that air when it closed. And that is generally very little.
Moisture is generally not a real problem, as the diff itself has much more potential to get some moisture inside. The diff has a breather hole, so every time when the diff gets warm/cold it sucks in a bit of fresh air and some moisture. (without a breather hole the diff would be weeping from the gaskets all the time as when it warms up the pressure inside would rise and that is a sure way to get oil leaks)
And in that system it is supposed to be 'lifetime oil', so compared to that 2 years in a closed bottle is nothing. Even brake fluid is generally useable for a very long time as long as the lid/cap closes good.

[rsutoratosu]

so funny thing, i went to grab my redline, it was close to empty.. guess i wont have to worry about it.. have to order a new bottle.. lol

[Efthreeoh]

Convenient topic....

So I may change my diff fluid today on my '08 Z4 Coupe. I plan on using BMW's current SAF-XO 75W-90 diff juice (it's what my '06 E90 325i takes). I'm assuming both diffs (the E90 and Z4) use the same spec oil?

Can anyone confirm? Thanks in advance.

[rsutoratosu]

Yes that would work..

http://blog.bavauto.com/10933/bmw-di...-applications/

[rsutoratosu]

E90 - pretty much any 75w90 that is bmw spec
http://www.pelicanparts.com/BMW/tech...eplacement.htm

[bosstones]

lol....good timing with this. I have a plastic jug (a reused jug...so no foil seal like a new bottle) filled w/ diff fluid from the dealer. I got it a few years ago but never got a chance to do the work (1st it was time, then not having the right stubby hex driver, then time...). It's been sitting in the closet under my stairs all this time. Sounds like it should still be usable.

[Efthreeoh]

Originally Posted by bosstones

lol....good timing with this. I have a plastic jug (a reused jug...so no foil seal like a new bottle) filled w/ diff fluid from the dealer. I got it a few years ago but never got a chance to do the work (1st it was time, then not having the right stubby hex driver, then time...). It's been sitting in the closet under my stairs all this time. Sounds like it should still be usable.

I did the same thing back in 2009 when I bought a gallon of diff fluid at the dealer in one of my cleaned out washer fluid jugs. I used it in 2009 in the E90, then more in the E90 in 2011. I had just enough left for the diff oil change I did yesterday in the Z4.

[rsutoratosu]

nice, i gave the mailman a break, i didn't prime my bottle, its coming monday after weekend... was hoping to do it during this coming weekend

[pokeybritches]

Originally Posted by GuidoK

As long as the lid has been on, there is no real moisture, only the moisture that was in that air when it closed. And that is generally very little.
Moisture is generally not a real problem, as the diff itself has much more potential to get some moisture inside. The diff has a breather hole, so every time when the diff gets warm/cold it sucks in a bit of fresh air and some moisture. (without a breather hole the diff would be weeping from the gaskets all the time as when it warms up the pressure inside would rise and that is a sure way to get oil leaks)
And in that system it is supposed to be 'lifetime oil', so compared to that 2 years in a closed bottle is nothing. Even brake fluid is generally useable for a very long time as long as the lid/cap closes good.

I don't disagree. To clarify, my point is that the shelf life has everything to do with the way the fluid is stored (mostly due to moisture), and you can't leave an open bottle of diff fluid on the shelf for years and expect it to perform as advertised.

Shelf life can be adversely impacted by improperly storing the fluid (as in storing it in an open container, in an environment with high humidity and large temperature variations). The condensate can react with the additives.

[bosstones]

Originally Posted by Efthreeoh

I did the same thing back in 2009 when I bought a gallon of diff fluid at the dealer in one of my cleaned out washer fluid jugs. I used it in 2009 in the E90, then more in the E90 in 2011. I had just enough left for the diff oil change I did yesterday in the Z4.

Good to know! Thanks! Color changed slightly but no sign on condensate (I crank the AC up when it gets humid in the summer/fall).