Checking/changing your vehicle's engine oil is one of the most important services you can do for your vehicle. Today's engines with VVT technology require oil presssure to advance and retard the engine's valve timing. This system relies on your vehicle's oil system to be in top notch shape. Using approved oil by the manufactor and servicing your vehicle every 3-5,000 miles insures your oil system stays in top shape. With the stop and go driving your vehicle endures in the DC area we do not recommend going past 5,000 miles even with synthetic. 3,000 miles with regular oil.