Do engines loosen up with age?

[bozzy101]

Working in the motor trade I've quite often heard people saying that engines loosen up with age, thereby increasing MPG etc. I have to admit that this is a view I've always assumed correct. Some of my other colleagues think it's BS though, and that the engines don't "run in"... It's a myth. I find this hard to believe, I recently ran a 1.6 Auris and the engine felt terribly asthmatic to begin with, loosening up nicely after 2500 miles. Perhaps a new engine over fuels for a few thousand miles? Maybe it beds in mechanically? Maybe it's placebo?

Does anyone know the answer to this??

[chrisxr2]

yes, the answer is yes they do loosen up and improve with some mileage. I have no scientific evidence to back this up.

[SkinnyP]

I find cars get faster and more fuel efficient with age, then they suddenly self destruct. I'm not kidding!

[V8RX7]

I don't know about mpg but certainly they can gain power (or reduce friction)

Several car mags / TV programmes have tested new V used on a drag strip and the older cars are faster - of course you'd really need to test say 100 to prove it with any certainty.

[Dave Hedgehog]

in my experience i would say they certainly do, probably due to the liners/piston rings freeing up a bit

but its normally most noticeable when you get about 20k miles on the clock

most German performance cars i have driven over the last few years appear to have a "run in" map that reduces the power a bit for the first 1000 miles or so

[J4CKO]

Yeah, I drove my mother in laws new E36 BMW 320i and was less than impressed, same for three years and say 15k, then my brother in law had it and battered it, high mileages and gave it some stick that it had never had, drove it again, different car, much more eager.

[vikingaero]

Most of the evidence of cars loosening up and improving are the car magazines who time test a nearly new motor with a thousand odd miles on the clock and then test it in xx,000 miles. In most cases the xx,000 mile time is much better.

[ging84]

engines do certainly have to bed in
i'm not convinced though that means there is any noticeable or even measurable difference in how it performs

i expect what has happened in your car is not that is has loosened up in any way, but you have become accustomed to it, although to be honest i have no idea what loosening up even means, do you mean it seems to have more power now? or change revs more quickly? or rev higher? all of these? something else?
either way i think it's in your head

[750turbo]

bozzy101 said:

Working in the motor trade I've quite often heard people saying that engines loosen up with age, thereby increasing MPG etc. I have to admit that this is a view I've always assumed correct. Some of my other colleagues think it's BS though, and that the engines don't "run in"... It's a myth. I find this hard to believe, I recently ran a 1.6 Auris and the engine felt terribly asthmatic to begin with, loosening up nicely after 2500 miles. Perhaps a new engine over fuels for a few thousand miles? Maybe it beds in mechanically? Maybe it's placebo?

Does anyone know the answer to this??

Speak to your other colleagues that have an ounce of common sense... Of course they do. As for the over fuelling option, another internet myth (In my time anyway)

May I ask what dept you work in?

[Urban Sports]

My 320d is now on 11,000 miles, when I got it last year new it was averaging 38mpg, it's now averaging just over 42 on exactly the same cycle.

[Axionknight]

I would say so, but it varies a great degree depending on the engine in question, my Volvo V40 has a 5 cylinder diesel engine that is now on around 25k miles and it seems to respond better than when it was brand new, fuel economy is harder to judge due to the way my driving schedule has changed.

Maybe it's just a placebo effect and I'm going crazy. I'd say diesels have a tendency to have adhere to this "rule" compared to petrol engined cars, from my experience.

[bozzy101]

ging84 said:

engines do certainly have to bed in
i'm not convinced though that means there is any noticeable or even measurable difference in how it performs

i expect what has happened in your car is not that is has loosened up in any way, but you have become accustomed to it, although to be honest i have no idea what loosening up even means, do you mean it seems to have more power now? or change revs more quickly? or rev higher? all of these? something else?
either way i think it's in your head

Well it gained a few MPG and felt a bit more eager through the rev range. I can't rule out this being in my head, but always believed cars do get better over time from reading such in car magazines etc. I was surprised when my colleagues said they thought it was BS though, and some of them have 25 years in the trade!

[bozzy101]

Dave Hedgehog said:

most German performance cars i have driven over the last few years appear to have a "run in" map that reduces the power a bit for the first 1000 miles or so

Perhaps this could be a possibility on modern cars instead of the old school approach of using a mineral oil to begin with and swapping out for semi synthetic 1 month in.

[karma mechanic]

Probably hard to see in this screenshot, but logging mpg for each fillup shows a steady improvement from about 1500 miles to about 10000 miles, 29 fill-ups over nearly a year. Nissan 1.6 turbo. Average for the whole time 35.5 mpg, worst 31 and best 44.99 (that was a tedious day).

[s p a c e m a n]

SkinnyP said:

I find cars get faster and more fuel efficient with age, then they suddenly self destruct. I'm not kidding!

Engines are always running at their best and most powerful just before they eat themselves, FACT

[oceanview]

iam sure my ex did

[sideways man]

Ex car mechanic here.

Used to maintain two rep's vauxhall cavalier sri.
One rep drove like your gran,the other drove like he stole it.

The thrashed one was miles quicker,though it drove like a bag of nails.

This backs up the theory that as tolerances increase due to wear,friction reduces thus increased speed. Up to the point it goes bang!

[Vyse]

You can also run the car in too carefully. If you don't thrash the car every now and again from new your car with most likely never reach its fullest potential and efficiency.

[delboy735]

As a young ( right ) car salesman, I had the pleasure of using a Ford Focus 1.6 Edge 3 dr thingy. It was a bit poor to start with. One of my "more experienced" colleagues asked me if i was happy with it's performance, no said I, so he took it for a spin to "loosen it up". Jeeez, it worked. Next trip home, much happier spinning towards red-line, just felt sharper and actually improved economy by approx 3mpg. His trick ?? Drive it up to about 60mph, drop it into 2nd gear ........so, I would never buy an ex demo now !!

[jonah35]

I've had loads of brand new delivery mileage cars and yes, they do loosen up. I find it takes maybe 20k miles for them to fully loosen up. They often sound better too. Performance gets better so does mpg.