05 merc 4.3 ??

[k5guy38]

What oil would you guys run in a 2005 mercucruiser 4.3 ?? This is my first inboard and read a lot of conflicting post. Thanks guys.

[Bamaman]

I'd be putting a high quality auto oil in such a unit--probably 10W30. I think the later model 4.3's are using a 25W40, but many come with catalytic converters. I don't think the weight is really that important if you're running the boat only in the summer.

If the boat is new to you, I'd also suggest an immediate change of the water pump impeller and lower unit grease. And I'd suggest having the hub grease changed. You don't want any surprises.