Manual Transmission Fluid Type

New Edit
I hate digging up old threads, but as I am the OP, I guess I'll let it slide :hi:

I'm finally getting around to changing out the manual transmission fluid and can't find the capacity ANYWHERE. Even the owner's manual doesn't list the capacity as it says it's a "Lifetime Fluid." I know I just need to fill it until it slowly drips out of the fill hole (being level of course), but for purchasing purposes, how much does it take?

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I'm beginning to feel some "notchy-ness" in my 1st and second gear, so I'm going to replace the fluid next week. I've heard of people using Royal Purple and saying it is a bad choice, so I'm looking to use the tried-and-true Redline fluids.

Here is my question. Some people recommend the MT-90 (along with pelicanparts.com) while I read a lot of places that say the 75W90 GL-5 Gear Oil is correct. The Redline application guide recommends D4 ATF and doesn't even list the MT-90! :facepalm:

What have you guys had success with?

Edit: 2004 E46 325CI coupe M54 5-speed manual