To fill the oil I typically fill the oil until I can see it just under the lower line in the sight tube. I know it will surely go up so as long as it's at that level I KNOW there is oil in the engine and I can ride it around to warm it up no problem. It's when there is NOT oil near the oil level indicators that you will damage the engine. It takes some real neglect to screw up an engine by running it low on oil so if you have half a brain you have nothing to worry about.