Dexron III is factory fill, I think. They don't make it anymore.
I use regular Dex/Merc (from a variety of sources). Might switch to MaxLife Dex/Merc from Valvoline, since my PS systems has 200k+ miles on it and assist is a bit stiff right after a cold start.
Suggest that instead of topping off that you disconnect reservoir and remove it (5 min job on the HL). Drain reservoir, rinse out any debris and then refill with new PS/AT fluid. Easy job and fresh fluid will help your seals and pump last longer.
It's very easy to disconnect the return, then turn the wheel back and forth and keep filling the
reservoir with fresh ATF until you get clear fluid which means you have flushed out all the old.
Single person job, but two are nice.
DO NOT start the vehicle. You will not be able to refill fast enough and it will spray all over.
Just place the return into a bottle and then jump in the cab with the ENGINE OFF.
And start to turn the wheel, Turn half a turn or so and then check the fluid level top off as needed, then just keep repeating till you get clear fluid and complete a full left turn and a full right turn.
If you want to make your life easier lift both front wheels and you can turn the wheel much easier.
For a pumping action to work just by moving the rack back and forth would require at least one one-way valve. Maybe the spool valve in the rack serves that purpose. Don't know.
So for grins and giggles, I tested funman's fluid replacement procedure. I'll be hornswaggled if it didn't work perfectly! Upon further scrutiny, it does appear the spool valve in the rack acts as a sort of one way valve. When you turn the steering wheel one direction, reducing the volume of one chamber, it pumps fluid to the return line. Concurrently the other chamber's volume, which is expanding, creates suction through the pump and pulls fluid from the reservoir. Turning the wheel the other direction, flips the spool valve while the opposite chambers compress and expand.
I did this with the front wheel off the ground and the engine OFF. Took less than 15 minutes, ALONE, to get clear/new fluid on the return line.
Yeah, I'll be doing it too. Same write up as the Tacoma DIY I've heard.
BTW, my daughter is inheriting my in laws '07 HL Limited probably in January. Had 3 deaths in the family in the last 5 weeks (2 of them both last Friday). So inheritances are trickling down with my FIL gifting the HL to my daughter. I have to familiarize myself with a 1st Gen again. :lol: Our '05 was a base model, so a limited will be a little different with the controls. I wonder if they have the same heater ribbon problem and whether I'll have to solder this one some day?