Some clarification: I have an external HDD that gets it power from the USB port. Even if I turn of the computer, the HDD won't shut down, because there's power-off charging on that port. This is my only USB3 port, so using an other port is not an option.
Mobil 1 Extended Performance synthetic oil is recommended for oil change intervals up to 15,000 miles or one year, whichever occurs first. However, if your vehicle manufacturer recommends an oil change interval beyond 15,000 miles and Mobil 1 Extended Performance meets the performance level specified, you can be assured that Mobil 1 Extended Performance will go the distance.
Synthetic Oil for cars (How many miles can you really go on it before changing it) I usually get Synthetic oil for my vehicle so that I don't have to change the oil every 3000-3500 miles. Now I go around 5500-6000 miles on Synthetic oil. However, I noticed as I went to the gas station that for Mobile Oil (synthetic) that it says you can drive your car for 1 year or 15,000 miles on it, whichever comes first.