Tranny and diff fluid

[CanadianDirty30]

So tomorrow i'm planning on changing most of my fluids in my 318is. The two that have me confused are the tranny and diff fluid. Every thread that discusses the correct weight for each seem to turn into a warzone. Just looking for a straight forward answer for which type of each I should buy, just for all around performance and reliability?

[ELVA164]

You won't get one, hence the warzones. The gear oils are a bit more straightforward in that you should use MTL or equivalent in the gearbox in your climate and assuming you have a limited slip, you'll want a GL5 oil with the friction modifier either pre-mixed or added in by you.

[noid]

I mean, you could always go to the dealer and get their fluid, at least you'll get what BMW recommends

Go to realoem, search by last 7 digits, go to transmission, grab the part number, go to "AUXILIARY MATERIALS, FLUIDS/COLORSYSTEM" and search your transmission, will tell you the correct weight and part number.

[nrubenstein]

The reality is that it doesn't really matter what you put in a G260, or am E30 diff once you get past the most basic minimum rating.

[roguetoaster]

If you have an M42 then you have a G240 gearbox, most of which take ATF. This will be indicated by a yellow/orange label on the case of the transmission. I have used ATF in my mostly daily driver 318i the whole time I've had it to no ill effect. I don't drive the car gently and change the fluid every two years.

As to the differential, I've used off the shelf Mobil and Valvoline GL-4/5 oils even after switching to a locking differential (the only oils I've seen are for limited slip use which are fine in an open diff). I just don't see the point in spending 2x those prices for Redline or similar for street driven/autocrossed cars.

For dedicated track use I'd get more expensive fluids, especially for the transmission.

[CanadianDirty30]

If you have an M42 then you have a G240 gearbox, most of which take ATF. This will be indicated by a yellow/orange label on the case of the transmission. I have used ATF in my mostly daily driver 318i the whole time I've had it to no ill effect. I don't drive the car gently and change the fluid every two years.

As to the differential, I've used off the shelf Mobil and Valvoline GL-4/5 oils even after switching to a locking differential (the only oils I've seen are for limited slip use which are fine in an open diff). I just don't see the point in spending 2x those prices for Redline or similar for street driven/autocrossed cars.

For dedicated track use I'd get more expensive fluids, especially for the transmission.

Awesome thanks, this helps a lot! I'll go out and look for those or something similar today.

[DER E30]

I put Redline MTL 75w in my trans and Redline 75w-140 in the diff IIRC. Think I'd put the MTL 90w in the trans if I was doing it again, the stuff that came out was really thick and the MTL was like water compared, Shifting got a little smoother but with more mechanical feel in the lever.

If you're up in Canada and park in the cold, a thinner oil is probably better though. The oil I have now has been ~30 degrees but no colder and was fine. (I park in the garage)

[jhaurimn]

MTL or MT90 works fine. I have mt90 in my 325i and even when it sits overnight in below 0 temps, I can get it to shift into 2nd fine, unlike the old fluid that was in there before.

I do recommend shifting into 2nd at 3k rpm in the morning when its cold, shifting at lower rpms will make it tougher to get into gear.

Mobil 1 75-90 for diff fluid, as long as its not a track car.

[ELVA164]

If you have an M42 then you have a G240 gearbox, most of which take ATF.

Important point.

[CanadianDirty30]

Yea ill stick with ATF for sure. I have an idea now of the weights im looking for, thanks for the help guys