If you need to mow wet grass, spraying vegetable oil on the blade will only remain for a few seconds due to the rate of the blade spinning and coming in contact with the grass. But take your time and mow slowly and empty the grass catcher often since it will clump in the mower. Don't mulch or simply blow the grass out on the lawn, you must collect the clippings otherwise it will clump on the lawn and potentially kill healthy grass. The most important thing is to have a sharp blade, a dull blade will tear the grass.