This is so other people don't make the mistake I made. I have a pre 1991 bravo1 upper and lower. No problems. I put a later sport master -2". I always try to use very good products. So I used a fully synthetic gear oil. Made for lower units and outdrives. 1st time out even cold there was a very slight delay into forward and reverse. Hot there was a 5 to 10 sec. delay. I was worried. Drained fluid overnight. Next morning filled with Quicksilver HP gear oil. I didn't do anything else. Back to shifting perfectly.
Hope this helps someone else

Yep, sometimes marginally worn cone clutches do not like some gear lubes.

I just did the same thing, changed oil in both Bravo1 drives, installed Amsoil synthetic , starboard drive shifts normal, port drive has a 7 second delay in reverse, forward is normal , using Mercruiser High Performance oil all was normal, ,,,what is worn out.
Thanks

So here is the problem, my cone clutch is worn, so the synthetic oil, which apparently is much slicker, causes a delay in shifting, so I am going to disassemble and replace the clutch and other worn parts as needed.

Monday I called 2 well know and highly advertised companies that Rebuild and sell Bravo Outdrive's, and parts.
I left a message with each receptionist for someone to please call soon me as I need to buy parts for my repair, was told at both places someone will call in 30 minutes,
as of Friday no one returned my calls,, here It is boating season, I need parts, I have money to spend ,
so Friday afternoon I called ,, Max Machine ,in Arizona,,, Aaron answered the phone himself, and was very professional and was familiar problem with my shifting problem so I will order my parts from them,

Some have had positive results deglazing the cone with valve lapping compound. Just some added info, years ago Volvo Penta use to recommend this 1995 and back in a service bulletin until they came out with the Nedox coating on their cone. I understand we are talking about merc - as for Volvo if you do not use a good quality GL-5 spec gear oil they will experience a delay when shifted - very common with their drive..

Yes I am using synthetic GL5 now, was using Mercruiser Hi Performance outdrive oil,

Thanks