With all of the oil tech geeks here, if anyone knows the answer to this, it would be here. I have been on the Honda boards and no body knows of an equivalent for a Honda Hydro transmission. I have done AI searches and have not found a clear answer. Everyone for the most part is unsure or does not know. I have seen one poster say he has used Amsoil 10w-30 Full Synthetic Hydraulic fluid and he feels it is fine. Another one other said he used Mobil 1 0w-40 as a top off fluid only. Can anyone say if they know of an equivalent Honda hydro fluid. Most of the answers are, I would not risk it. Just use the Honda hydro static fluid. OK, I get that. I do not want to get into why I am asking. If that is your answer, please do not bother. Unless you are OCD and need to reply for your mental health. That I understand and am happy to help you in that way. Thanks in advance.