Your Best Digs also recommends the Sun Joe mower but the reviewer also added a number of caveats. He found it will get the job done if you prefer to only bag and just have $100 to spend. However the clippings compartment filled up quickly for him. And the height adjuster felt flimsy and required adjustments on each wheel.
Next you will change the oil. To lower oil viscosity and get it moving freely run the engine for a few minutes. Now shut the engine off and roll the mower onto a piece of cardboard or drop cloth. Close the fuel line (if your mower has one) and unhook the spark plug as before. Find the oil filler tube and remove its cap. Often the cap also functions as a dipstick.
Top 5 Lawn Mowers recommends the Sun Joe MJ401E to people with a small yard who dont want to spend a lot on a mower. The reviewer liked it overall for many of the same reason one might like any electric mower (no fossil fuels lightweight etc.) but he also noted that there were only three height positions with the lowest scraping the ground. And due to its 14-inch blade it takes longer to mow a lawn.