Generator when cold should have an 1 1/2" or so of coolant showing in the tank, a bit more when hot. The yellow cap is the oil dipstick. You will likely find that the genny does not use any oil between changes, however it is prudent to check it once in a while. I just finished my full annual service and we had about 125 hours, it had not consumed any measureable amount of oil.
2015 Legacy 340KP
2012 Wrangler Sport