I bought my 2013 Silverado 2500 gasser this passed summer & one of the first things I did was get the oil changed with mobile1 full synthetic. It's been about 4,700 miles since then now. At what interval should I change the engine oil with it being fully synthetic? I know that the oil filter is a limiting factor... What's a good oil filter to use?? I'm going to start doing the oil changes myself. Thanks!