I run pretty low miles on my 3.5EB. I've finally decided on my oil as long as it stays reasonably priced and performs as well with regard to fuel dilution and shearing in the SP GF-6 variant. Castrol Edge every 12 months until out of Powertrain Warranty. Castrol Edge EP every 24 months after Powertrain Warranty (Not to exceed 10,000 mi OCI). Now I'm sure this is going to cause a lot of uproar but I can find no correlation between fuel dilution level and drain interval or timing chain life and drain interval (as long as the IOLM Mileage isn't exceeded) The two highest mileage trucks I know have had 7,000 - 10,000 mi OCI and the two 11's I know with timing chain failure before 100,000 mi had 3,000 - 5,000 mi OCI. Now 24 months is going off the reservation but I can't find a reason other than fear or speculation not to.