H3T Auto trans service; drain and fill or flush?

[SedonaBound]

The "new" T Alpha just clicked over 45K miles and the previous owner hauled a trailer quite a bit (a Subie race car I think) so I want to get clean fluid in the auto trans ASAP. What's the consensus on a flush & filter vs. just draining and refilling at this mileage. I'll do the diffs and TC too.

 

[Best4x4]

Just do a filter and 5qt of new ATF. You'll be good to go.

 

[3rdH3]

I have read hundreds of articles on this very subject. I decided to alternate. You will get good arguments on both and some have their own way of doing a combination of the two. I do a lot of short trip runs so I change fluids ahead of even the severe use chart. I did a drain and refill with a new filter (generally called a drop and drain) at 30K and did a flush at 60K. At 90K I will do another drop and drain. FYI, GM recommends the drop and drain. The differentials and transfer case are so
easy, I do that at the same intervals. Many would say that is unnecessary, but I have never heard of a failure by changing fluids too often.

 

[SolidusJ]

Drain with filter and then add a plug, drive 10 miles and then drain and refill. When I was draining the over fill it was brand new ATF.

 

[chaos254]

Is our trans pan steel or aluminum?

 

[Best4x4]

Aluminum with a steel pan