There are aftermarket fluids which can surpass the oem fluid but also plenty of fluids that aren't as good as oem. If he used a cheap mineral based dex/merc instead of the Honda fluid he would have problems, but Maxlife, Amsoil, Mobil 1 all make fine multi vehicle atfs.
For ATF Z1 MaxLife should be okay or at least it says so on the bottle.
However ATF DW-1 is differnet. It does not say that on the MaxLife Bottle.
The only ATF that says DW-`1 is the Honda DW-1 and the Castrol Multi Import ATF says
Recommended HONDA / ACURA ATF-Z1, ATF DW-1
I dunno why one would say recommended and the other says suitable.
even in my owners manual it says its suitable to use 10W30 Oil in the trans fluid.
and the Castrol Transmax Full Synthetic Multi-Vehicle ATF says Suitable for ATF-Z1, ATF DW-1,
Personally I say go with the REAL GENUINE HONDA APPROVED DW-1 even if your Honda was a around before DW-1 was around.
The owner of the shop is correct.
also power sterring ... I have heard that you can use the prestone stuff but it depends on your climate.. I have read very hot or very cold areas the Prestone Powersterring Fluid can give problem.
Even Advanced Auto has there own house brand of Honda / Acura Power Sterring Fluid and I dont use it.
I just drive to the Honda dealer and buy it.
I know some people get lucky with with MaxLife ATF...
however untill I see a car come from the factory that says prefill with Valvoline ATF / MaxLIFE ATF
I dont see why they wouldnt do it.... I mean GM puts Factory pre-filled with Mobil 1 on Corvettes and I know other cars say Factory pre filled with Castol Edge Syn got Engine Oil. So if aftermarket brands are so good how come they do use it?
Reason::: as one person said a transmission is different then a engine...
They Factory does all kinds of tests and simulations to figure out what ATF is the best and then they use that one...
Find 1 new car that says Factory fill Tranmission with any after market Trans Fluid.
I bet you cant find 1.