What voids a Jeep warranty?

I just moved to Ohio from Georgia and went to fill up my car only to see insanely high gas rates. Why are they so expensive here?

I know that oil gets darker over time, but I feel like it’s happening in my engine way too fast. I changed my oil, checked it a few hours later, and it was already brown. What might cause engine oil to turn dark so quickly?

I’ve recently started developing some discomfort and pain in my wrists during and after driving. While pain medication helps to alleviate some of the pain, I am worried that there might be a more severe underlying issue at hand and that my driving practices are exacerbating it. Can driving cause carpal tunnel syndrome?