Hi,

I just got my new GT and I have to be honest when I say this is the first new car I have ever bought... all my previous cars were used.

The car had 5 miles on it and I have driven about 60 miles so far and being a GT I stupidly and unknowingly started to give it a lot of juice at almost every stop sign and traffic light as it turned green to see what this engine is made of!

I then remembered something about a break in period and started taking it easy.

I have a couple of questions:

1) Why is there a break in period? Why shouldn't we drive the new engine hard (In theory)?
1) I have noticed that I'm getting 8.7 MPG which I know is incredibly terrible, how long does it take the engine to start using normal amounts of fuel and getting reasonable MPGs?

I know some of these questions might seem stupid but I'm a newbie so bear with me


Thanks

 

I had many of the same questions and my research thus far has turned up the recommendation that the first 1000 miles be considered the break in. The one thing that seems consistent in how people recommend driving is to vary your speed throughout that period and avoid prolonged driving at any given RPM.

Another suggestion I've seen that made some sense is that you check the oil level throughout this period as some may be lost.

I doubt you've done any damage since I've read of numerous people driving them pretty hard immediately after picking the car up.

I'm curious about the answer to your third question as well since I've read reports of everything from 500 miles to 2500 miles before fuel economy begins to level out.

My car isn't due to arrive for another week so I can't speak from experience, just my reading thus far.

 

The search function is such a wonderful thing.
https://mustangforums.com/forum/5-0l...in-period.html

 

Haha fair enough, but I also have the question about the consumption which separates my question from the rest

 

Read the manual, all the answers are in there. You will get poor fuel economy for the first few hundred miles and the engine is a mechanical device with mechanical parts that needs to wear in and seat together properly before they get excessively heated.

 

As much as I hate to go easy on anything. I believe the manual say 1000 miles. Vary speed and RPM. I'll get those 1000 miles over quick so I can let her rip.

 

The only mention of break-in I found in the manual is a mention in the fuel economy and MFT sections that say, respectively:
"Do not measure fuel economy during the first 1,000 mi (1600km) of driving (this is your engine's break-in period)...."

"Note: In order to allow a break-in period for your vehicle, you may not be able to create a Vehicle Health Report until your vehicle odometer has reached 200 miles."


For something as important as a break in period I would expect the manual to be more thorough.

 

Page 188

 

Ah, there it is. Thanks

 

well we 'll se how it goes, but I let mine rip after about 150 miles..