So I discovered why I had excessive back pressure tonight. The 3" exhaust went into the flowmaster and came out as 2ea 2" Well the one side had the tail pile stuffed about 3" into the muffler. I figured that is what was causing my excessive back pressure. When we were coming home from MO and I would have to punch it I would hear one hell of a wired noise. It would go away after a little while. So tonight I checked my oil and it was a little low. I need to change it anyways.

But my question is, if you have excessive back pressure, can it cause you to burn oil?

I cut off the tail pipes at the backside of the muffler, it sounds like it was breathing much better, perhaps I should have done before our 2700 mile trip.

 

I highlighted your problem. In many cases, a "flowmaster" actually flows worse than the stock exhaust does. Even without the plugged outlet, just having the flowmaster would likely cause more back-pressure. How low on oil were you? Many people here on the forums report half to a full quart low at around 5k miles, depending on the mileage.

 

It was about half a quart low for the first time. What muffler do you recommend? It came with the flowmaster when I bought it.

 

Magnaflow or go slow!

 

excessive oil usage or loss is cause either by excessive valve guide clearances, bad oil rings on the pistons or too much internal crankcase pressure (plugged PCV valve)

 

x2

oil just doesnt "burn" on its own. it has to make its way past a seal of one sort or other.

#8 cyl on most engines are known for issues due to lack of air and breathing. they tend to run hotter and causing the first sign of excessive engine wear. (back rear cyl pass side)

if it is burning then i would start by pulling each plug from each cyl and inspecting as you go. compression test would tell you which direction from there.

but no, whichever muffler you choose should not cause oil burn.

 

Well, good news, I didn't burn any oil! It turns out that it was the way the truck was sitting. I am wondering if when I add the leveling kit would it make a difference on the dip stick? It is irritating when you add your 6 qts of oil and it still only reads half way. I have never had a more temperamental truck.

 

Next time you change it and it has the proper amount of oil in it. After being started and run for a little bit, let it sit awhile. Then pull the dipstick and make a notch in it where it is reading and this will be your new full mark.
The 2001 F150 I had with a 5.4L held 6qts of oil. When I changed the oil and added 6qts as required, it always read 1/2 qt low. It always did this, so when I checked it and it showed 1/2 qt low, I knew it was full.
My Hemi always shows full after a dealer performed oil change with 7 qts of oil.
Luckily, it always shows full after 3K miles too