I know that many people prefer to hose their mowers down with a garden hose. I admit I have done it. Still doing that is risky. If water gets into the wiring air filter or engine you could really do some damage. Hand washing with damp rag is a drag but also your safest bet.
Place a drip pan or other container on the side of the mower with the filler. Carefully tilt the mower so oil drains out and into the pan. Discard the spent oil into a proper disposal vessel. Now slowly pour fresh oil into the mower. For the specific type of oil you need check your instruction manual. Make sure to add only as much as your particular model requires. Remember to let the mower sit undisturbed for a few minutes so the oil settles properly inside the engine.
More than 1100 buyers have left five-star reviews of the LM2101 on Home Depots website. Austing wrote a review after a year-and-a-half of ownership and was impressed with how lightweight and quiet it is. He shared a story of hitting a metal pipe in his yard with the mower. It damaged the electronics and EGO sent him a brand new mower to replace it. Buyers also appreciate that the battery only takes about 40 minutes to recharge from dead.