I know this may be a strange question but here goes... I have a 2008 Honda Civic with an automatic transmission in it. Honda calls for Z-1 transmission fluid. Z-1 has been superceded by DW-1 fluid. I was looking at Rock Auto's website and they show Dexron 6 as being compatible with my Civic. I also saw where RA sells a friction modifier (ATP brand AT-203) which supposedly makes "any conventional" Dexron fluid, such as Dex 3, compatible with the Z-1 fluid. The main reason I am asking all of this is because I also have a 2008 Suburban and I have about a case of Dex 6 left over from the transmission service I did on it. So if the full synthetic Dex 6 will work as a replacement for the Z-1/DW-1 then I would much rather use it instead since it is synthetic. If I chose to use it do you think the friction modifier would be necessary. Any help would be appreciated.