Do any of you guys run that Royal Purple synthetic oil? If so, how long have you ran it and do you have the stock block?
I have heard of Ford telling people that the RPL oil can ruin the 5.4 motor. Don't know if that was the newer three valve 5.4 or our 2 valves, or if that makes a difference.
I've always put regular Valvoline through mine and change it every 3,000 but I was thinkin about stepping it up and using some synthetic stuff and everyone has told me they love Royal Purple.
Or should I just use Mobil 1 / Castrol synthetic?
I have heard of Ford telling people that the RPL oil can ruin the 5.4 motor. Don't know if that was the newer three valve 5.4 or our 2 valves, or if that makes a difference.
I've always put regular Valvoline through mine and change it every 3,000 but I was thinkin about stepping it up and using some synthetic stuff and everyone has told me they love Royal Purple.
Or should I just use Mobil 1 / Castrol synthetic?