Manual calls for Dexron III, but since that is no more what is best to use?  I see so much conflicting and indeterminate information.  Subaru HP? Valvoline Maxlife? Dexron VI? Aisin T-IV? 

Has Subaru issued any kind of definitive recommendation?

Thanks.

Check out dextron IV - the description will no doubt tell you that it’s suitable for vehicles where dextron III is recommended/required.

Cheers 

Bennie

You mean dexron VI?  IV & V apparently don't exist.  Most word is the VI is not the same as III and often doesn't work well in older trannys, even though the claims say it is backwards compatible.

 

The 4EATs are not picky about what fluid to use.

 

You can buy Dex III, it's usually labeled Dex/Merc (Dexron/Mercon). That's the cheap conventional stuff, works great, meets all the specifications. I buy 2.5g house brand jugs of it at Fleet Farm.

All Dexrons are backwards compatible. So you can use those. Most will be synthetic (certainly anything you can find new)

Subaru officially superseded to HP. So anything that meets Subaru HP will also work. This will all be synthetic. This is what we carry and use (I work at a Subaru dealership)

 

I honestly think the change to HP was just to use a synthetic so they can extend suggested service intervals and/or in an attempt to reduce resistance for better mileage. I have not found any part or seal that changed part number when they switched to the HP. If I had a newer 4EAT, I'd dump conventional dex/merc in it.

Edited August 20, 2025Aug 20 by Numbchux

Amsoil has a great fluid.

Went to the local dealer.  The parts guy said use HP.  When I questioned that he went and asked the main mechanic and he said use dex/merc.  I guess I will either use Valvoline maxlife or the HP.  I use the Amsoil products but their ATF is just so expensive and you need like 12 qts to do a complete change.

Drain

Pull the trans coolant line and put on temp lines into a drain jug.

1- Fill Trans

2- Start it up and let the trans pump all the old fluid out the line you put on the trans coolant into a gallon jug.

3- When the drain jug is 3/4 full - Turn car off. 

Repeat 1-3 until the fluid is nice and clean.  

Put the trans radiator coolant lines back on and start it up.  Fill to full COLD.  Test drive, check fluid Full to HOT.

Takes about 3 gallons for a full flush this way.