My 2018 LSV23 was 7250 lb with full fuel, coolers and toys for the day. Cat scale verified. Add 2,000 lb to that 5.700 lb and your probably close.

I can only add a little to this.  My 2003 came with 15w40 and contacted Indmar and they said 15w50 Mobil 1 was fine and wouldn't void my warranty.

Replaced my burned up RF 12” sub (smelled like dumpster fire) with a new one, and replaced my internally shorted RF Punch P600-2 (orange light on anytime connected, and made a second sub smell like electric death) with an M5-1500X5, but still no sub activity.  

Turning it on or off at the deck gives no change in sound.  Bass up or down no change.  

Checked sub with a battery and the Sub reacts to battery test (touch wires to +/- AA terminal).  The amp appears to power on.  No warning lights.  Sub channel lights up blue.  Switched the presets off.  Adjusted the gain.  Adjusted the crossover.  Nothing.

i looked at the back of the head unit/“deck” and see one small wire running to ???  I don’t know where the RCA outs originate from (physically).  The rest of the system (other amp, tower speakers, boat speakers) all work fine.

Help?  I’m $1500 into fixing the sound system on a 4 week old (to me) boat and haven’t gained anything…. Any ideas or related experience ??

I read it, just don't believe it.  Your moto oil shouldn't be burning nor effecting temps in the cat so not sure how they can claim any impact on them.  I'm sure there's a way, but I'm not a believer with a fair amount of engine experience.  I'm sure it's not a problem jist find that marketing claim a bit bogus.

I have run into this on past cars and one boat once.  In my experience, every case turned out to be that the amp was bad.  In one case it burned the speaker up as well.