Your '90 owner's manual probably says to use 10w-30 engine oil, because Honda didn't have MTF back then. They introduced 'genuine' Honda MTF around '96 or so, and it's compatible with the trannys that call for 10w-30 engine oil.

So if your owner's manual calls for something else (like GL5 gear oil???) then use that. But if it calls for engine oil, Honda MTF is a little better.