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Is "break in" and MPG a real thing?

12K views 36 replies 16 participants last post by  GraniteBlue05 
#1 ·
I keep hearing how vehicles need to "break in" for "a few thousand" miles before you start getting your max MPG. Is there science behind that, or is it just a matter of the computer adjusting to our driving habits and/or us adjusting to the vehicle?

Regarding the diesel specifically, what mileage would you consider it "broken in"?
 
#2 ·
It's a real thing. The rings have to seat against the cylinder walls. Whileas they never actually "seal," the seal does improve and your combustion events are kept inside the cylinder rather than blowing by into the crankcase, which for obvious reasons is more efficient.

There isn't a set in stone mileage at which rings seat, and there's not an exact point where they go from unseated to seated persay.
 
#3 · (Edited)
I keep hearing how vehicles need to "break in" for "a few thousand" miles before you start getting your max MPG. Is there science behind that, or is it just a matter of the computer adjusting to our driving habits and/or us adjusting to the vehicle?

Regarding the diesel specifically, what mileage would you consider it "broken in"?
Or ya know 400 like it says in your owners manual :wink2:
 
#13 ·
Why some people respond to posts without actually reading the question is completely baffling to me...

So I know what the manual states as break-in, however that does nothing for the MPG, which is the subject of my post.
 
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#6 ·
Can't say that I have noticed any difference in mileage from 100 to 3600. It has been pretty consistent. It got better when I started running 89 octane by about 1.5 mpg, but that has been the only change I have noticed. I started doing that on the third tank I put in the truck. I can say the truck ran better after it was broken in. Better throttle response.
 
#8 ·
I agree with the break in thing. I tried 91 once just for an experiment and didn't notice any change in performance or MPG. 89 is usually only 10 cents more a gallon, if it even gave me about a half MPG I think I would break even and probably get a little better quality gas at the same time. The truck runs great so I doubt it "needs" it though....
 
#7 · (Edited)
IMO there is not a whole lot to the break-in MPG thing. Sure rings seat and bearings do too but I doubt the new rings would cause a low enough compression to matter much. It seams to me if the rings wore in so much when new they would keep on going and be worn out in no time. Maybe the combination of all the moving parts "breaking in" could raise the MPG? I'm no expert on the subject, and its hard to research anything anymore cause the net is so full of crap......:(

edit: kind of like this post right? ahahaha
 
#10 ·
I can assure you that seating rings (which is essentially the only thing involved with "break-in" aside from a few heat cycles for the health of valve springs and such) is a real thing. We run an engine dyno and watching with a blow-by gauge you can actually see the difference when it starts to seal up. Crankcase pressure drops off and power increases. Oil will get less diluted and you will use less oil as well, contributing to efficiency all around. Does it always measure appreciably in MPG? That's really hard to say. It is real though, there is no contesting it, and ring seal contributes to efficiency in ways that can't be disputed.


Bearings don't break in.
 
#15 ·
Reading the manual is definitely a good thing. But common sense for your 1st oil change isnt one I adhered to, and with good results.

I did my 1st oil change and the amount of metal flakes I found amazed me. Since we have cartridge filters, it wasnt hard to see.

Not trying to start a debate here about it but again, Im glad I got all those metal particles out of my engine ahead of their schedule.

PS, I barely noticed any MPG change from the day I started driving it.....around 18.5 since the day I got it and Im at close to 12K now.
 
#16 · (Edited)
By my data the definitive answer is "Sometimes".

The Wife's TDI Wagon certainly improved as it broke in. Also interesting is that the last 9 tanks (post emissions flash) seem at least as good as before.


My CCLB 2.8L Colorado on the other hand does not appear to have been positively affected by break-in. Retirement and change of driving habits occurred somewhere in there and that possibly muddied the data. I would not expect those changes to negatively affect MPG however. The 9 mile commute wasn't exactly the ideal mission for this.


...Another noteworthy note... We live in PDX and bought the Golf Wagen in PDX. It's first tank was pretty much business as usual. I bought the Colorado in Bend and drove it home so the first tank had substantial highway miles. If you were to drop that first tank down to the first commuting tank or lower the story may have been different.

The first spike in the early commuting data was a trip to the Steens. I have a pic of the truck on the Alvord somewhere here. The later spikes were Death Valley (Lower than Steens due to Nevada speed limits) and local camping trips. The 17.9 following an unusually high tank is likely the result of foaming on the fast prior fill.

So there you have it - And I'm charging exactly what it is worth!
 
#17 ·
This is very helpful, thanks mate!
 
#19 ·
The break in deal is a mixed question.

In years past there was always a break in for all engines. It was critical and if not done right it could be a major issue years from now.

Even when Synthetic oils arrived it was a major issue to seat rings and was to be avoided till broken in.

Today it is a mixed bag where some engines are broken in from the factory. Some cars like the NSX stress this. Others are not broken in and they do recommend doing easy miles the first couple hundred miles.


But the reality is even if you don't follow the instructions odds are good that you will not blow the engine up or suffer issues. Todays engines are built to very tight tolerances and will survive the lack of break in.

It is still a good idea to follow the manual but if it were true all cars have to follow it exact nearly every Corvette would have a failed engine.


Oils today also do a better job too and many come from the factory filled with full syn.


Now if you build an engine at home the needs are still much like the old days as you are not building to the same standards as the factory. Also many oils lack the zink needed to break in a solid tappet cam. Factory engines are all rollers now so it is not a factor anymore either.


The engine getting loser is a variable. Some will many won't. Much of the things like the valve train are all roller. Cranks are better fit to be low resistance from the start. Rings do seat but it is not like it was in the past with better materials.


Much of the drive train is optimized to be low resistance from the start so the changes are much less dramatic than in the past.


The long and short of it is follow the instructions as they are different on many applications.
 
#21 ·
Today it is a mixed bag where some engines are broken in from the factory. Some cars like the NSX stress this. Others are not broken in and they do recommend doing easy miles the first couple hundred miles.


But the reality is even if you don't follow the instructions odds are good that you will not blow the engine up or suffer issues.
There is also more than a little evidence that putting the engine under torque loads early has a positive effect on ring seating.
 
#20 ·
Fondupot - It's called "Road Trip HD" and unfortunately only available for Apple. We still have a couple devices in the house so we're still tracking the diesels with it.

I don't collect data on the bikes any more but the KTM ran pretty rough off the showroom. I remember setting idle back down for each tank.


The ZX636 MPG improved with break-in but much more again when I started advancing ignition timing for low throttle settings. I think this thing runs about 6% on a freeway cruise. Factory timing was late on the bottom end for a benign throttle response. Torque off the line improved as well.
 
#24 · (Edited)
My diesel sure seems to be getting more efficient with a few miles. It used to be a bit of a challenge to break 30 mpg, now it is easy. 40 is the new 30! Was driving along and for the Hell of it checked my trip screen. She managed 42.5 mpg today during a calm and flat 65 mph 48 mile freeway stretch with the cruise set.

It got a bit of a "drive it like you rented it" break in. Well, not completely, but the engine got run up and down the mid revs with varying loads and exercised during every outing. Has used not a drop of oil and is running great. Quite happy with the efficiency of my MiniMax.

Have always run in new engines (4 wheelers and 2 wheelers) as GraniteBlue05 describes, or the "MotoTune" method and it has always worked well for me.
 
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#26 ·
I'm pretty sure the "MPG will get better after break in" rumor was made up by salesmen and service writers...."Don't worry, your MPG will get better when it gets broke-in, it's normal" ahahahaha..
 
#29 ·
I'll endorse that last remark. Just read the recommendations in the owner's manual and take it easy at first. In my case, I take it easy all the time anyway. I don't know if my mpg has improved over the break-in period but it doesn't matter because it is at best a third-order effect. The first order effect is how one drives.
 
#33 ·
As for if it's a thing or not I couldn't say. While I always follow the manufacturers suggested break in, I do not posses the knowledge or equipment required to tell you definitively that break in results in a tighter engine. But if the engineers that designed the vehicle think it's needed, and it's not something ridiculous like taking the first 20,000 miles, then why not?
 
#37 · (Edited)
Apologies for this kind of thing to all.

More words will validate nothing and just trash the thread even more.

I'll take the high road rather than resort to egocentric, condescending endless wordy diatribe that really says or contributes nothing.

Good night to all.:grin2:
 
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