Originally Posted by
AtTheRiver
Using a petroleum lubricant, especially one with solvent properties (WD40) on nitrile or rubber gaskets scares me as well. You are probably OK but a good alternative is a slightly diluted dish soap in a spray bottle to lubricate old impeller to help with extraction. I endorse the paint can openers but take several with you as mine bent.
As far as frequency of changing, I spend the extra and put in Globe run dry impellers which I change every 3 seasons (about 150 hours) and have never had a failure since switching to Globe in previous inboards.