My Infiniti dealer wanted nearly $300 for a transmission fluid flush / fill and $130 for the rear diff. I mean actually flushing, not just a drain and refill of trans fluid - over $400 total. They told me only THEY have the proper transmission fluid.
The mechanic shop where I get my 68 fleetwood serviced charged me about $250 for BOTH the trans flush / fill ... AND the rear differential fluid exchange. No matter how rich/ not rich you are, when you can safely save $150 on a maintenance item, you do it. But you have to go to a shop you trust and they MUST have the machine that performs this procedure. My mechanic told me the trans fluid was pretty clean and free of debri. My car has nearly 80k miles and since I bought it used, no idea if this was ever done before. As for using ONLY an Infiniti dealer for this service, here is what I found and it confirms exactly what my mechanic told me:
Nissan matic J is a semi synthetic JASO 1A spec ATF actually made by Castrol and sold to nissan who then puts their name on it and slaps all the dire warnings on everything in their vehicles about it but the fluid is nothing more than Castrol Transmax J which Castrol makes to work in all JASO 1A spec Japanese autos.
http://www.tds.castrol.com.au/pdf/2701_ ... 650_03.pdf (the Castrol data sheet for Transmax J)
I had no issue with my transmission at all, but I felt that 80k miles is a good time to replace it. As for NOT doing any service if you don't have trouble with it? That just seems like a risk to me. I reckon the horror stories we read about came from peeps who didn't go to a reliable shop with good mechanics, or peeps who did it themselves and mucked it up.
BRAKE FLUID:
I'm definitely NOT a qualified mechanic, but in Europe, one of the things tested in your official inspection is brake fluid and lots of cars fail and have to get the fluid changed. According to what I've read, after 3 years, your brake fluid has enough moisture in it that its boiling point is too low to meet safety requirements. Here is an interesting article I found which promted me to have the fluid changed with my brake job.
http://www.workhorse.com/Portals/0/Why% ... %20wip.pdf
I'm interested to hear from Inifiti techs or other mechanics on the forum regarding what they think about this.