Merc Cruiser 4.3L I/O engine - service/maintenance interval

[TyeeTanic]

Hello all.

I just bought my first boat recently, a 20 ft Taho with a 4.3L merc cruiser IO engine.

The book tells me I have to service it every 100 hours - that would be like every month for me!!!!

Is this for real????

Most of my time is idling while trolling - is it really necessary to pull the boat out of the water every 100 hours, or is this overkill??

Thanks.

[traveling man]

100 hours is not overkill in my opinion especially if you are trolling alot.

[Misty IV]

I agree with Chris. 100 hours on an engine that spends a lot of its time trolling is not overkill. I follow that maintenance schedule with my 4.3 MerCruiser, as well, and I think it is money well spent. Ask L&M about it, and he will definitely steer you in the right direction. Pretty sure he will agree with the 100 hours.

As a side note, last season at the end of the year, I sent a sample of my oil into Blackstone Labs to be evaluated for wear. Granted, this batch only had about 50 hours on it, but I always change my oil before I put the boat away for the winter. I use the MerCruiser 25W-40 oil and Blackstone reported back they found no unusual wear and did base the report on about 75% trolling, 25% under power. They suggested I go to a 75 hour OCI. Again, I only had 50 hours on that sample because of when I changed it last. I'm going to send in a sample this season at my 100hr mark and see what they have to say about it.