VLO's high cash coverage means that, although its debt levels are high, the company is able to utilise its borrowings efficiently in order to generate cash flow. Since there is also no concerns around VLO's liquidity needs, this may be its optimal capital structure for the time being. Keep in mind I haven't considered other factors such as how VLO has been performing in the past. I recommend you continue to research Valero Energy to get a better picture of the large-cap by looking at: