Shear Stability v Frequent Changes

[HyundaiAbuser]

I currently have a 94 Mazda b4000 w 145k miles on it. I know that manufactures such as GM have recommended newer low viscosity fluids, Dex VI, over their previous, Dex III, for their older vehicle applications due to the greater shear stability. Im assuming this is over the 30k mile change interval recommended in the owners manuals of these vehicles. My question is, how much would i have to consider that in a 10k interval scenario. I currently sit on about 5 gallons of conventional Dex/Merc and dont drive my truck incredibly often. Therefore the truck would probably tank before i'd run out of fluid, but i would like the transmission to be in as best working order as possible. Is the full shearing from roughly 7.?cst to around 4 accounted for in the design of these transmissions? Is it more beneficial to keep a fluid in there that fluctuates in the upper half of that or one that sits right in the middle for the entirety of an interval (assuming id be using a synthetic replacement for a 30k interval)?

 

[Linctex]

Unless you do a lot of towing, it isn't going to matter.

 

[HyundaiAbuser]

I do on occasion tow a very small trailer with a 7 foot kayak in it. Probably less than 1000 lbs total. This makes up about 1/5 of the driving.

 

[WyrTwister]

What did Mazda specify in 94 ? Dexron III ?

 

[HyundaiAbuser]

Mercon is the recommended ATF

 

[MolaKule]

Manual or automatic transmission?

 

[ka9mnx]

Mercon is a direct replacement for Dex III. They were literally interchangeable in the day. Mercon V is the replacement for Mercon and more closely matches Dex III specs than Dex VI. It's what I use. What you already have is just fine for your application. Your sitting on about 5 fluid changes.