Transmission Fluid Question (long)

[Jason Davis]

After reading up on se-r.net and the archives, I decided to change my tranny
fluid to Redline MT90.  My car has 58,000 miles, and I remember reading
somewhere that it needed to be changed at 60,000, so two birds...
Anyways, I went down to the local NAPA store.  The owner is a personal friend
of my grandfather's so they usually shoot me pretty straight.  Unfortunetly I
was dealing with the owner's son.  He knows alot more than I do...but...
Well, after requesting to order the Redline, He says I could just use this
Valvoline 75w90 synthetic, as it is the same stuff.  On the bottle, however,
it said it was a GL-5, not GL-4.  After quoting the archives about GL-5 being
pretty bad for our GL-4 trannies, he basically says I'm an idiot.  Something
like "There isn't any difference.  You can't always believe what you read"

Then he says that I don't even need to change my fluid, even though he never
looked at my car.  He claimed that if you change the fluid after about 40k
miles, it can screw up your bearing pretty bad.  The "harsh detergents" in the
new oil will "over-clean" my transmission.  Does this make any sense?  I'm too
much of a neophyte to tell.  Could there be some kind of correlation between
new transmission oil and the 5th gear pop-out?

Sorry to ramble on, and thanks for any help!
Jason Davis
98 200sx SE-R
College Station, Tx