We have a '02 f150, 4.6L, has around 500,000km's, used 5w20 mineral from new (Ford or Chevron), either Ford, Wix, or Donaldson filters, 5,000km intervals. It started using oil slightly about 3 months ago, I told the guys to run a 5w30 from our lube supplier, a mineral with a -40c pour point, and...