Need Advice. My VX is ready for transmission fluid change. Last time was a flush 18,000 miles ago at the Isuzu dealer. (VX has 55k on it now) It currently has Dexron III in it. I would like to replace it with the closest thing I can to the original Dexron III but as you know, Dex III is no longer made. All I can find is the Dex/Merc multi-vehicle oil. Some have reported slipping when using Dexron VI so I am hesitant to try that. Need advice as to what mineral oil is working well out there. (I’m not ready to switch to synthetic). Can you guys tell me if you are having luck with a specific formulation by a specific manufacturer? Any advice is really appreciated.