Reading the Westbeke engine manual, in the winterizing section, they say to remove the impeller for theWinter and put the cover back on, and then reinstall the impeller in the Spring. I have never done that. For the O-ring, I use whatever's handy, usually Super Lube grease, but not that you only need a very light film, don't goop it on. You might stuff some grease in among the impeller blades to protect it before it draws a prime. The Westerbeke impeller kits come with a small vial of grease for that purpose.