Which Spark Plug Should Be Used In A Kohler 15 HP Lawn Mower Engine?

The 15-horsepower Courage and Command lines of Kohler lawn mowers use Champion RC12YC or equivalent spark plugs. Alternatively, the Courage line also uses Champion QC12YC plugs. Command vertical shaft mowers also use Champion Premium Gold 2071 plugs; Command horizontal shaft mowers also use Champion Platinum 3071 plugs.