Mckay's recommends an Oil Change Service every 3-5,000 miles as it helps to eliminate costly repairs, keeps warranties valid and increases gas mileage.
Synthetic oil does everything that regular oil does but it does it better and longer. The reason is because the molecules that makes oil slippery are smaller in synthetic oil, thus, it lubricates better. It also isn't affected as much by contamination and breakdown as ordinary oil - thus you can go longer between oil changes. There are some considerations before converting to synthetic oil, so ask us before making any changes. This definitely should result in a noticeable increase in gas mileage. We recommend changing every 7,500 miles.