[fmpr26]

I know this is older but it may help a lot of people by keeping it going. Prices of Kia Dealer ATF and PS fluids have gone through the roof.

I have used the Walmart SuperTec ATF that says it covers SPIII. I believe it is Dexron VI/Mercon LV.

It has been 3 or 4 years and working fine.

A lot of people on BITOG have said Valvoline Max Life has worked good as well. It is more afordable if you buy it in gallon jugs.

As far as PS fluid goes, I have used Amsoil and it has worked fine. It is a bit pricey compared to most ps fluids you will see at Walmart but cheaper than the Dealer.

I used Idemitsu type HK (SP-III) in both the power steering and the transmission.
The PSF-4 has an operating viscosity around 7.5cst, but is full synthetic. ATF +4 or Dexron-III should also work in the power steering application.
ATF +4 has more friction modifier than SP-III, while Dexron-III has less friction modifier than SP-III. The consensus for ATF+4 is in transmission use is unclear, but it should be a much closer match than the Valvoline maxlife (around 5.8-6.0 Cst)

EDIT: The role of friction modifiers in ATF seems to be commonly misunderstood. Friction modifiers reduce, not increase, the coefficient of friction between the clutch discs. This is especially important for cars that use a "partial lockup" torque converter, which requires slippage to occur within the TCC. If this slippage cannot occur, the computer senses this error and will attempt to disengage and re-engage the TCC. This phenomena is commonly referred to as "torque converter shudder" and can damage or destroy a torque converter clutch.
The disadvantage of friction modifier is that it makes the rest of the clutches "slippery" as well, increasing engagement time and potentially increasing wear.
Transmission engineers, when designing a fluid/gearbox, must find a good middle ground between too much and too little friction modifiers.

 

[fmpr26]

Good information….thanks.

Valvoline last three transmission drain & fills ( before that Kia brand ATF fluid) . Ravenol SSF in last PS drain & fill. So far all is well at 142K. and going on 18 years.

Here is a good chart showing the viscosities of different ATF blends. PSF unfortunately not included. The use of lower viscosity fluid is made possible by the changeover from sprag-based gearboxes to clutch-to-clutch systems. Bearings and other hardware has also been re-designed to work with the thinner lubricants.