I just put in some of Honda's new fluid DW1 and according to what it says, it has much better heat resistance than the previous Z1. I put some in my car the other day and I was pushing it pretty hard with my tranny cooler and I have yet to notice any transmission problems. I would highly recommend putting in DW1 as brand new DW1 compared to brand new Z1, DW1 seems to not only make shifting smoother but quicker as well. Probably gonna do 2 more drain and fills in the future to utilize the full potential of it since it's currently blended in with my leftover Z1.