Hello everyone,
So I'm newer to the forum and have owned my 13' STX 5.0 3.55LS for a couple months now. When i first got it, I drove it slower than a grandmother for gas mileage only to realize this motor likes to pushed a little. I still do easy starts, and roll to stops(I normally try to roll and never get below 5 mph up to a red light as it turns green) only to see a consistent 15-15.5 mpg on the digital display. I know the display could be off but it seems pretty accurate with how many miles I get to each fillup. As of right now, I let it short shift first and from second always let it work its way up to about 21-2200rpms before each shift.

I just wanted to know if I should drive it harder or easier to see better mpg, or is 15.5 about all i'm going to get. This is with probably about 80% city driving. (I live in central NJ).

 

I'm in the same boat as you. I have about 880 miles on my truck and have owned it for about 3 weeks. I baby my truck (old school I guess) to let the engine break in, but I'm eager to hit the gas to see what this 5.0L can do. Of course, the cost of fuel is also why I haven't punched it.

 

love my 5.0, revs nicely and will not hesitate to drop a gear and get up to highway speed quickly. I drive conservatively on my morning/evening commute of 45-60mph and readout shows 18-20 depending on traffic.

 

Very old school and not good for new motors. You want to at least drive it the way you normally would but avoid a constant load for long periods. The easy break-in method leads to more oil consumption than a motor that was driven hard at break-in. The motor needs to rev to seat the rings properly. The added benefit is that the motor will output the max power it can due to good compression (again, from properly seated rings).

This is my method and have never had a new motor that consumed oil over the life of the vehicle (cars, trucks and motorcycles).


Edit: Here's a site (****ty but great info) http://www.mototuneusa.com/break_in_secrets.htm

 

Two years on mine and I drive hard, average 14.8mpg and that is mostly city. Take it on a 300 mile highway trip, you will see better results. Remember the sticker is 14-19, so 15.5 in the city is good if you ask me.

 

I am in the same boat as the others. Just got my truck 4 days ago. Was told by the dealer to run it at different speeds for the first 1,000 KM (6,000 miles). No towing or no use of the cruise.

I was wondering if putting on a K & N cold air intake was a good idea? Any ideas or thoughts on that subject?

Thanks for reading my post.


Michael J.

 

I've built a couple of motors and a I quickly got schooled on a few urban myths.

A new motor doesn't need much of an elaborate break in. It happens very quickly, I'd estimate within less than one hour of run time. Being easy on the motor is not the best, sure-fire way to get a good break in. I'd suggest as the article above mentions, break in occurs best under load and under high cylinder pressure (and vacuum).

The best thing, in my opinion, is to run the vehicle up to moderate speed at medium to hard throttle, and then let the vehicle slow down through engine compression braking. Both those exercises create a good deal of pressure in the cylinders and will help get the best ring seal possible. Do that a few times and the motor is broke in for all intents or purposes. If there is a problem, it is a problem from the build or the parts and it'll break. No amount of babying will fix a bad build or faulty part.

The sad part is, the motors in most new trucks you buy on the lot are already broke in by the time you sign the papers. A lot of vehicles I test drive on the lots have anywhere from 2-20 miles on them. Heck, even my custom ordered Super Duty which I watched roll off the transport truck had almost 25 miles on it, and no one in my state even opened the door to it beside me. Trust me, the rings in a motor are broke in by the time you put 20 miles on a truck.

It's the rest of the drivetrain that needs a few more miles to wear in and break in, like the axle's ring and pinion and such. Still, I'd argue that everything is broke in after a 100 miles. It's new, but it is broke in.

To the OP,
My 2011 F150 with the 5.0 and 3.73 axle gets about what you are seeing, upper 15s to low 17s depending on how long I idle and how much wind I have to buck.

 

Drive it like you stole it. no sense in babying it.

 

Bought mine May 7 2013 and to put it nicely I ran the **** out of the truck for the test drive,Unless im going to work I drive it like I stole it, I've got 3,5xx miles on it. Drive a 14 mile commute to work daily, 11 miles of that is straight hwy rest is city (4 redlights). If I hold it at 60mph hwy and 35 city for a round trip my "AVG MPG" is always in the 18.8-19.6mpg range.

Ive towed my 6,000lb Travel Trailer + ATLEAST 800lbs of equipment for a 30mile one way trip with rough curvy roads that require alot of slowing down 40-60mph alot. At the end..I averaged 10.7mpg I'm happy with the 5.0 to say the least

 

Beyond the towing for the first 1000miles drive it like you stole it. In simpler terms take it on the highway and put your foot down that doesn't mean drive it wide open and be liability to yourself and others on the road get it from 0mph to 90mph by putting your foot down.

Also believe your maintenance service manager and salesperson that you do not need to do oil changes at 5k under normal driving conditions. If you consitintly towing or driving the **** out of it fair enough. The manual tells you the oil change frequency it's accurate. If you feel you're just to old school to change your mindset it's your money feel free to change it more often.