Everytime I take my truck to the dealer for an oil change the invoice lists Motorcraft 5w-20 as the oil used. The other day I was looking over the Motorcraft website and saw a link to their bulk oil. The website does not list 5w-20 as one of the oils available in 55-gallon drums, only 5w-30, 10w-30, 15w-40, 10w-40, and 0w-30 are listed. So, does this mean that the dealer is using a 30wt. and just listing 5w-20 on the invoice? I have asked for a sample for a voa from their bulk containers but they say its against their policy.