Looking at these two engines. 6 vs 8. The v8 has a 10 mm smaller piston and 4mm less stroke and is .4 liters larger and the Merc runs on 87 octane vs 89 for the Yamaha.
I would think the Merc should live longer as rom to rom the Merc pistons travel slower and weigh less than the V6 yamaha.
there is a bit of a weight diff with the yamahas being heavier.
i also like the larger 5.44” lower on the Merc but at the same token I can’t find the dimension of the Yamaha 300 lower unit.

price in both engines within a few hundred bucks

Anyone like to give me some feedback. Thanks in advance Rm.

Lots of good upgrades on the 2021 Yamaha 300. Gear case is 4.75" on the Yamaha, but materials used in cylinders and gear case etc. are of superior quality to Mercury.

The Helm Master EX option with autopilot and digital built-in electric steering is handy too. Your current marina, which is Yamaha biased will continue to put up with you, and

last but not least, Yamaha is blessed by Virgen Del Carmen in Colombia.

thanks for the info. Looks like we are going with 300 yamahas by default. But the dealer says the engine with the electric steering aren’t the commercial grade versions of their engines which I don’t get

rm, did you check the classifieds here

i need to buy them from a dealer and they must be new engines as Colombia has a lot of red tape for importing vehicles and engines

I have a pair of 4.6L V8 Mercury 300's on my pontoon boat and they are impressive engines. I run them wide open often and don't stress it one bit. The other thing I really like about them is they are extremely easy to work on, the oil drain, the oil filter catch basin, and the removable cowl are super nice for maintenance if you do it yourself. Yamaha has an amazing reputation though and I'm sure they are excellent engines too.

i was in the process of buying a pair and the dealer screwed me and sold them out from under me. My boat runs everyday and the dealer doesn’t want people in the slips going out daily which I don’t get. Zero involvement on their part for my captain and mate to take the boat at 8 am and return it at 1:30. My currently marina won’t let me stay if I buy mercs lol. Wtf. I will buy yamahas now as our existing engines have over 2k hours and could puke any day now. I just don’t want to be dead in the water with no engines coming into high season Merc 300R’s or 450s will go on my manta cc. I might even buy a pair of low hour suzuki 300s for now as merc is 40 weeks back ordered on 450s from what I understand. Thanks for the info tho