Well if someone else has a 4.7 doesn't like synthetic, I cant guarantee that mine will either. Thats why I started with a syn blend.

 

4.7's drop valve seats like nothing I ever seen. That'll be your problem long before the lubrication system fails.

 

Never heard of that problem

 

The difference between 16 and 13mpg is roughly 20 percent+/-
The difference between 22 and 11mpg is roughly 50 percent+/-

I agree brakes could do it but 50percent mpg reduction seems like too much.

 

I was in the engine shop picking up my race motor last week and the machinest showed me 8 4.7 heads with dropped guides. The topic cam up because I mentioned I was looking at buying a dakota with a 4.7. Well I guess I'll stick with the old B3500 van 5.9 w/ over 300,000 miles on the original engine and trans.

 

If you were getting a 50% MPG reduction because of dragging brakes you would definitely notice it. Im sure there would be lots of smoke or noise.

 

Thats what I just said

 

Yep you guys know a lot more about fixing cars on the internet. Too bad you can't actually fix the OP's problem directly. I thought the idea of the forum was to make up as much garbage as possible which has no factual meritt? Just trying to contribute my fair share with the bogus dragging brake idea. Oh and you do realize that many people are totally oblivious to the condition of their cars even when the tire is totally flat and they're blasting 80mph down the highway as chunks of rubber go flying off... still no reaction or inclination that anything is wrong.

 

Actually this is the first time I've engaged in posting replies to anyones problems on any forum anywhere.

 

You actually gave percents.

Huh, I just figured that since the 4.7L was still around it must not be too bad. I have heard of problems with the H.O. 4.7's though.