Oil in use one year and a few days. Towards the very end of interval was ~3,400 miles over 5 days of towing a 7,500# (total) U-haul trailer with vehicle to Moab from Alabama and back. (FWIW, averaged 8.1 mpg on trip out and 9.1 mpg on trip back. Engine worked pretty hard.) Day after trip was a ~18 mile each way trailer return and then a few days later a 4 - 5 mile warm-up before oil change. Oil mix was 5 quarts Pennzoil Ultra Platinum 5W-20 and 3 quarts Pennzoil Ultra Platinum 0W-40. Ford specs 5W-30. I have a good bit of xW-20 to use up from a prior application so therefore the mix. Widman calculator suggested a 10.3 cSt @ 100°C start.
Kind of disappointed with fuel dilution. At 1.8% it probably accounted for most of the decrease in viscosity. At least it stayed in grade.
Kind of disappointed with fuel dilution. At 1.8% it probably accounted for most of the decrease in viscosity. At least it stayed in grade.