Originally Posted by GaryG

I've only used the approved Motorcraft blend and the approved Mobil 1 5W-20 in my '05 FEH. I didn't see an increase or decrease in mileage with either of these oils.

I did see a ~1/2 to 1 1/2mpg tank average increase in mileage between the approved motorcraft blend 5W-20 and approved dino Pennzoil 5W-20 in my '02 Explorer and '02 V6 Ranger. The mileage drops off to about the same as the Motorcraft blend at around 3,000 miles.

The only reason I made the change was Walmart stopped selling the Motorcraft 5W-20 Synthetic Blend for a period of time, so I was forced to buy the Pennzoil which meets or excceeds the Motorcraft Blend specs at that time. When the Motorcraft specs changed for the '05 FEH, I swithed back to the new spec Motorcraft Blend to see if there was an improvement in my '02 Explorer's mileage and there was no change over the old Motorcraft Blend.

Walmart started selling the new Motorcraft Blend and also started selling 5W-20 Mobil 1. Since I change my oil in the Explorer every 3,000 miles, and the cost of the Blend and Pennzoil are about the same, I use Pennzoil for better mileage. I switched to Mobil 1 5W-20 in my '05 FEH, but found no change in mileage over the Motorcraft 5W-20 Blend. There seems to be no change in mileage after 10,000 miles with Mobil 1 in my '05 FEH, so I continue to use it. I don't use the Pennzoil in my FEH because I know it will not last over 3,000 miles or the time it takes me to put 10,000 miles on my FEH.

My personal opinion is that the straight dino Pennzoil 5W-20 will increase my mileage in my '05 FEH for a short time over both the Motorcraft Blend and Mobil 1 5W-20 oil based on my experience with my '02 Explorer and '02 Ranger.

I will change the oil in my '09 FEHL for the first time at around ~5,000 miles and plan to use Mobil 1 5W-20 for 10,000 mile oil changes there after. If I wanted a slight advantage at say the MPG Challenge, I would consider using dino Pennzoil during that competition.

GaryG