Do you have to use the mercruiser drive oil that you get from a dealer? When I winterized my boat I didn't have time to run to the marina so I stopped at an auto parts store and got a high Quality gear oil the same weight as the mercruiser stuff. Do I really need to change it before use or will I be O.K.
I personally don't think there is a difference. Any thoughts. By the way its a bravo one.

as long as it is a 75-90 hypoid type oil you should be fine. the merc hpf really is the best though

you can not mix hp gear oil with an organic oil, I would not recomend running anything other then merc hp drive oil esp in a bravo !!!!!!!

If you are under warranty you have to use Merc products. Merc HP lube does have additives to help break down any H20 that gets in there.

It also has additives for heat dissapation,friction,ect (bravo uses friction to shift)

Many folks have had good luck with other synthetic gear lubes in Bravo drives such as Mobil 1, Royal Purple, etc. I use Amsoil's Marine Gear Lube and have had many, many trouble free hours with it in my Bravo drives. if what you got at the auto parts store was a quality 75W-90 synthetic, I wouldn't bother changing it out. Teague supplies his Platinum Bravo drives with Amsoil gear lube.

there is a thread from a few months ago on this topic,

you have to be careful as you do not want to use a 0 friction sysnthetic in a bravo drive ( this is highly debated) but the fact of the matter is bravo uses friction to shift...

red line and royal purple are zero friction dont know about the others

Not to say Merc will consider policy work if you're out of warranty, but if you are using what they tell you there is some liability on their part.

My real world experience with Amsoil shows it works just fine. I haven't toasted a cone clutch. Maybe in a high HP application you could slip the clutch using a pure synthetic, but I don't have that problem with my measly 375 HP!

I use Amsoil Syn 80W-90 per Teague and have no problems. Runs great.I use Mobil 1 20W-50 VTwin in the 502 Magnum with good luck as well.