Before I changed my own oil, I went to VIOC and had them use Castrol GTX. This of course came with a Valvoline filter (VO-47 I believe) that is smaller than the Motorcraft filter I now use, it also didn't seem too fit well - it always had oil running down the side. When I began changing my own oil with a Motorcraft filter the leak stopped. I never had any trouble that I was aware of (excluding the poor fit), but I won't use them again.