engine/drive oil suggestions?

[CDeal1]

I have a 1989 Mercruiser 454 (300hp) with a bravo drive. Does anyone suggest using synthetics? Climate is North Central Arkansas. Very Hot and Humid July/August otherwise pretty darn nice. I just purchased the boat so this will be my first oil change.

[MOP]

Merc Hi Performance is good and is syn oil, or if you want Red Line is suppose to be the very best. I have Merc HP in all my drives but thinking of trying RL in the Blackhawk. Engine oil is tough, there have been many discussions up here on it, me I do like syn oil but it depends on engine hours. I feel the engine should have 25-30 hours before switching to syn and not over about 100 hours, that is just my slant on it. Try a search on oil there is very good input from guys that really know oils.

Phil

[gold-n-rod]

Same motor here, a 1991 model with +/- 240 hours.

Over the years, I've run the Merc oil, (25-40 IIRC), Valvoline Super HD 30 weight, and last year switched to Royal Purple 15-40 (full synthetic).

The R-P worked great for me. It's going in again this year.

HTH,

goldnrod

[RedDog]

Well in mine, I use Merc Hi-Perf in the Bravo and Valvoline Racing 40 in the big block. I haven't been convinced on the synthetics yet...

[Donzigo]

I have twin 454's in my 1989 Z-33. I'e been using straight SEA40 Valvoline oil for many years. In Florida's heat, the engine is always working hard. Using the heavy 40 seems to make sense to me.