I bought my first Jeep and went with the Diesel. With that was wondering if anyone could help. First off. It's awesome. Glad I went with the Diesel. Makes the experience that much better. The dealer told me the def had a shelf life of 6 months. It's a second car for me so it's not driven daily. Do I top off the def or wait till empty? Second there's a definite delay in throttle response. Any suggestions? Thanks in advance.