Castrol Transynd in a Dex II automatic?

[fdcg27]

I used the search function, and some members have used this fluid with good results in various car automatics.
My understanding is that this ATF meets Dex IIIG.
The stuff appears to be pretty thick, almost as thick as a thirty grade A3 engine oil (HTHS=3.4!), and much thicker than Castrol IMV ATF, according to Castrol's not totally comparable PDS sheets for the two ATFs.
I found some of the Transynd on CL for a dirt-cheap $8.00/gal.
I am thinking that a few drain/fills on the old Imprezza might be a good idea.
The old dear calls for Dex II.
What does everyone think about using Transynd in our old Imprezza?

 

[JHZR2]

Im considering it after reading that it is OK for old viton rubber seals while dex VI is not.

I dont know what is in older non-gm ATs specced for dex II... thus why this is appealing.

 

[fdcg27]

Right, and this was a problem with Dex VI in some of the earlier Allisons.
You are considering Transynd for your 123s, and maybe the MT of your 318?