[ReelMagic]

Not sure what the right answer is but I would look at your manuals to see what/if the manufacturer recommends what to do to winterize. If nothing is provided. I would write the engine manufacturer itself.. Everyone has their own thoughts and reasons on what/how they winterize... I owned a 1997 31 Open with 454 FI Crusaders for more than 10 years. Winterizing them was quite simple as far as I'm concerned. I added a fuel stabilizer to full fuel tanks, ran the motors for 15-20 minutes; then changed the engine oil/filters and fuel filters. Restarted the motors and used a fogging oil (recommended by Crusader) injecting the fogging oil into the throats of the throttle body till the engine really, really, smoked and then shut the engine down... Had more than 1800 hrs when I sold the boat and the buyer is still doing the same.... Know that MPFI is somewhat different so you most likely need to modify the process. I believe stabilizing/filling the fuel tanks, running the engine to get the stabilizer fuel throughout the system is what is really needed. M2C