But can YOU verify it's the fluid? or just an assumption....( no need to answer like I know you want to, not an actual question
)
I bet if you got to the nitty gritty a majority of the fluids are the same or within 1-3%. Just buy them all and send to laboratory for read out......
Anyways, enjoy whatever you decide to do OP!!
Go over to Bob the Oil guy. Look at their analysis. I've probably gotten deeper into what's in oil/fluid than a lot of people. There's just certain stuff it pays to use OEM unless you know there is an absolute, concrete, non-OEM substitute.
Like I said, I know ZF stuff well. I am sitting on a boat with two $55,000 marine diesels connected to two $10,000 ZF transmissions. I've spoken with the people at ZF. They are brilliant, make a good product, but very specific about how they want it maintained and filled. For frame of reference. They want those filled with straight SAE30, non-detergent. Literally, $4 a quart Wally World oil. And they even tell you that. No detergent.
There's also a lot of variables too. Did the people who used aftermarket fluid who have issues have it serviced right? Was the vehicle in general abused?
But that's my other point. Just eliminate the variables. If you can't find anything better and/or that crosses over to OEM...just use OEM.
There is a lot of speculation that ZF uses/designs their stuff around Ravenol products. I'm a diehard AmSoil guy. I'd used AmSoil mouthwash if they had it. I went OEM fluid in my trans and t-case.