This strength of Xtreme Clean functions really well as a degreaser if you are servicing your machine. It will literally cause the grease and oil to melt away!
It will also clean the thistle sap, grass staining, and gunk from both the blade and the catchment. Whilst the lawnmower is standing upright spray the underside (usually through the catchment hatch is easiest) with the Xtreme Clean. Give the entire area a good soaking with Xtreme Clean. Wait four to five minutes and then hose the lawnmower down. You want to use quite a direct blast from your hose. All of the thistle spa, grass buildup, and gunk will flush away.
Remember the Xtreme Clean is non corrosive and cannot damage your blade or the mower.
Protip – do this on an area you don’t particularly care for. Right over your prized piece of lawn is not a good idea. The Xtreme Clean won’t damage the grass, but the gunk looks ugly and is difficult to collect and dispose of.