I've had the truck for 11 years. I've switched from Mobil 1 regular oil to synthetic at around 50k miles and have ran synthetic oil ever since along with either Mobil 1 filters, Amsoil filters, and one K&N oil filter along the way. According the mechanic the weird thing is that the bottom chain was the one that jumped two teeth along with the worn guides/shoes but, the both camshafts (SOHC) will still in time when he replaced the parts. Hopefully, I can get another few years out of mainly just for winter driving since they use salt here and all the snow so I need 4x4 here.