Mixing oil types (5w-20 mixed with 10w-30)

Threads like this always amaze me. Most posters are correct, but there are still a few that take the time to post an opinion, rather than stick with the facts. The high and low level indicators define the operating range. These values were carefully calculated by the designers of the engine. They expect that you will monitor the oil level to determine that it is constantly in the operating range, and add a quart when the level is even with, or below the "low" indicator. This silliness of trickling a few ounces in, or even worse "just add a quart and go", is not how it works. Adding a few ounces of oil is no different than waxing your rig since you just know that it improves the MPGs. If that's how you chose to waste your time, carry on, but it's not something that matters in the least.

Is the vehicle sitting level? Has the engine sat for a few minutes to allow all the oil to return to the pan? Is the level is the operating range? If the answer to all three is yes, you're good to go.