When I had my old FJ40 and left the hubs locked I noticed a difference (major decrease) in milelage, so it has to make a difference, but what have you guys noticed in your 4runners?

I'm predicting 1-3 MPG better. What have you seen???

 

It depends mostly on your diff and transfer fluids. Slick synthetic oil lets the gears turn without much resistance so not turning them won't make much change in fuel economy. Crusty old oil=more resistance. Unlocking with that will yeild a slight difference.

 

I've heard about 1 MPG for the newer trucks. Hey any improvement is good with these trucks right?

 

my gas mileage changes A LOT depending on if my hubs are locked or not... i can probably get 50 or more miles to a tank with them unlocked.... but there could be other factors in there too. i havnt tested more than a couple of tanks. i only lock them if it has snowed realy recently or if i am using 4x4. unlocked seems to make a big difference...

 

It's probably because my truck is older, but I have noticed a marked decrese in MPG with the hubs locked. Also around 50 miles per tank. Right now since it's dumping snow I'm leaving them locked, as I do when there's a possible need, but otherwise I make sure they're set to free.

 

That equates to more than 2 MPG looks like. Wow - a mod I must do soon.

 

I just did mine, so when the weather gets decent, I'll do a test of locked vs free