I had a bunch of links I searched for but can't find some and some don't work anymore. So looking for recommendations and opinion for tranny service(fluids for all atf,center and rear diffs) I live in the interior alaska and am looking to use full synthetic fluids. Thanks 

Look In or get an owners manual for weights and capacities. Those trans are pretty robust and don’t have many issues  

vast majority of gains will be from new fluid not type of fluid.

someone just posted excellent results with their ATF change / find  that thread.  

I have a fsm. Capacities and weights are known. I was researching for brand recommendations thru the board. This is the first auto subaru i have bought(for the wife) Lucas oil, royal purple, and oil,mobile one, ect. And some reasons why the opinion. The previous owner did scheduled service but used conventional fluids and the car runs great and has no issues besides replacing a broken fog light and with the deep cold -40 -50 coming thought this would be a great place to ask for opinions. Thanks again

GD has posted what he uses in his shop and probably has the most quantified reasons for doing so.  Id start there. Are you new maybe, If you know how to search, look him up.  lmdew also just posted some ATF info for the same trans within the past couple months as well.  my internet connectivity is terrible or I’d do it now and give you some links.  

Will it see any summer temps, weight or steep grades that warrant an ATF cooler?  

You could also add a filter.  Subaru added a filter starting the next year - 1999.

Those 98 4EATs do great, robust machines.  Front diffs are almost as prone to issues as the trans, I feel like I’ve actually seen more.   Rear diff failures are nearly unheard of.

I found it. Here is what GD does in his shop.  Read it all, as he mentions what his shop does for all Subaru autos - newer CVTs and older 4/5EATs.  Yours is the ubiquitous 4EAT trans almost every Subaru had from 1990-2004.

 

I'll suggest Valvoline MaxLife (Dex III/VI w'ever) for the 4EAT. a lot of the fluid stays in the torque conv.  3 drain and fills with a little driving between gets you over 80% new fluid - there are ways to do a complete swap of course, search for those ideas. If you are having any delayed engagement, a bottle of Trans-X on the last fill really does refresh seals. Sneak up on the hot (operating temp) full line - the marks are only a few ounces apart. Run thru each gear and check while idling of course.

The Subaru new OEM ATF-HP may be a little better for you with extreme cold..... not sure. It is a thinner viscosity and a 'must' for the 5EAT in 05s - up.

 

consider using a turkey baster with a short hose and refresh power steering fluid with some new ATF too.

 

 

 

name brand GL-5 should be fine for the diffs, synthetic might be best in your harsh climate. You might look for the synthetic 'blend' at WalMart - inexpensive and some folks seem to like it.

 

take the FILL plug out first on the rear diff, that way, you know you can get fluid into it. If you drain, then can't bust the fill loose, can't drive the car! I used my floor jack on the handle of my breaker bar. Those things were TIGHT.

 

I used these items to help with the rear diff and the trans/front diff;

 

 

 

 

 

 

 

 

Edited October 9, 20187 yr by 1 Lucky Texan

Thanks for the responses.

I too, have a 98 Outback, recently changed the ATF. What I did is to drain and fill three times, with short drives between drains. Doing this gives a good drain, as only about half the ATF will not drain from the system. I am happy with the results.