[valiant67]

Flush first. That way whatever you are flushing out does not contaminate a new filter.

 

[Doug D]

All can tell you is my dealer recommended dropping the pan and change the filter/fluid the first time, then a flush the second time and then continue to alternate the two types of service. Unfortunately the only way to change transmission filter is to drop the pan - can't do that if you just have a flush.

And I think the engine is running during a flush so if you were to do a drop-the-pan service and then do a flush the transmission would be low on fluid for a few moments until the new fluid from the machine could start pushing the old fluid out. Maybe IC can confirm.

My general comment is not too worry too much unless you are having transmission issues. The last time I checked it was running about $285-$300 to do a drop-the-pan-change-filter service on my Ram and just over $200 for a BG flush. One dealer would do both but it was about $400, but even he said that was overkill.

ATF+4 is a good synthetic fluid and even only changing half of the fluid is more than sufficient. My Ram has 168K on it (545RFE transmission). Had a drop-the-pan service done around 125K miles (actually was part of repairing the internal linkage that broke but that was another thread).