Has anyone used this stuff and would it be safe to mix with M1 multi vehicle ATF? I've drained and filled the transmission around eight times with the M1. I think I'm going to stay with the M1 but I had the Castrol on hand? They both say Dex IV and below so I figure it will work with the first Toyota in my signature block. It requires Dex III. Where is Castrol Import ATF HM on the food chain of ATFs?