Question. I have an external tranny cooler, and want to flush the entire system. Can I just disconnect one of the hoses connected to the cooler and let it drain? (in a container of course). i have about 10 Quarts of royal purple i'm waiting to top it off with and everywhere i go to get it drained wants to use their own stuff. Thanks for the help.

 

Disconnecting a hose will not drain very much. You would have to run it and let it pump out while adding at the same time.

If you use an approved ATF+4, there is rally no need to flush. (Unless the fluid was burned, or severely contaminated)

I don't see Royal Purple on this list:

Please note Licensed ATF+4® Brands have been updated as of March 25, 2011.

Advance Auto Parts ATF+4®
Auto Extra ATF+4®
Auto Zone ATF+4®
Carquest ATF+4®
Castrol ATF+4®
Castrol Transmax ATF+4®
Chevron ATF+4®
Citgo Transgard ATF+4®
Coastal ATF+4®
Federated Auto Parts ATF+4®
Great Wall ATF+4®
Havoline ATF+4®
MAG 1 ATF+4®
Mobil ATF+4®
Mobil Super ATF+4®
Mopar ATF+4®
NAPA ATF+4®
Northland ATF+4®
O’Reilly ATF+4®
Parts Master ATF+4®
Parts Plus ATF+4®
Pennzoil ATF+4®
Pennzoil S6 ATF+4®
Petro-Canada ATF+4®
Pure Guard ATF+4®
Quaker State ATF+4®
Quaker State S6 ATF+4®
Ravenol ATF+4®
Service Pro ATF+4®
Sinopec ATF+4®
Shell Spirax S6 ATF+4®
Super Tech ATF+4®
Valvoline ATF+4®

 

So royal purple Tranny fluid is no good? My mistake on the details. I had planned on letting it pump out completely. My question is would it damage anything to let it pump out all the way?

 

I'm not saying Royal Purple is no good. I'm pointing out the fact it may be different from the brands whose ATF+4 gets periodically tested for conformity to the fluid required by the 42RLE.

You can't let it pump out completely. Those who do it this way add fluid as it is being pumped out. If the old stuff looks bad, it will be apparent when it's all replaced by the new.