Why people believe FE will improve after first service?

I personally have never experienced that FE has improved due to Engine tuning after 1st service. It might improve due to change of driving style and due to knowing your car better.

When car is new it does come duly tuned,new car officially does not require any run in period but each time I see few posts in forum whre people say " FE would be better after 1st service".

Do share your thoughts.

Well, it has to do with friction. A new engine has parts that have not yet been completely seated against each other so as to have minimum friction.

The point here is not the 1st or 2nd service, but rather the time between the purchase of the car and the time when the 1st or 2nd oil change is done (which usually is done during the 1st and/or 2nd service). This oil (and filter change) removes all the ground away metal particles that would otherwise remain between the various rubbing surfaces not allowing them to move as freely as they could. Once the oil is drained, all this grit also comes out and effectivle the engine parts are now well seated and have very little dirt between them, end result being reduction of friction and thus an improvement in engine performance - which is seen as an improvement in FE (ECU basically ensures that RPM, pick-up etc stays the same - but due to less friction these are achieved with lesser fuel).

Even though engines are run-in from factory, they are not fully run-in simply because in factory it is very difficult to emulate typical day-to-day driving and load conditions - plus I don't think they would run-in a car at the factory in the same way and time that it would be done when driven on the road by its owner...

@Master

Well most new diesel cars in family are giving optimum FE right from day one but every petrol car which i know has given 2-3 kmpl more after first service. And every car, diesel or petrol feels way better after 5000 kms.

@Rohit

I totally agree with you. Even I am a firm believer of run-in period and advice everyone who buy new car to follow run-in procedure meticulously.

The increase in mileage is due to a combination of all the points mentioned. That is:

1. When the car is very new, we will not be very familiar and hence be more careful for the first few days/weeks, driving it in gears lower than the optimum and driving slower than required.

2. As Rohit mentioned, run-in of the engine and oil change.

3. Other parts between engine and wheels (like gear, differential gear, coupling, bearing etc) also becomes smoother after some running.

First servie as such has no effect on milegae (except psychological) since nobody touches the tuning or something, or change the oil in most of the current models of cars during first service (unless it has run too many Kms). All they do is check if everything is OK and do a water service.

Tomy

Well explained by Rohit and others. The only thing I would add is that cars are never tuned these days like older cars. It is just that the ECU learns your driving style and adapts the tuning to match it. Also, I would advise all to sincerely run-in their new car for at least 2k kms and that would do wonders for them in the longrun. Also, though some cars have first oil change at 10k kms, its better we get an oil change at 1-2k kms in the beginning due to the reason rohit has mentioned. There are many instances where metal filings or poweder is found in newer engines during an oil change.

I didn't know that. I changed the oil only after 1 year (3 rd service) @ 4000+ Km as per the manual (and information from service centre). Maybe I should have done it during 1st service as well (like diesel models).

Tomy.

i didnt understood whats 'run-in engine' actualy mean.

Please elaborate

thanks

Well said Rohit, This is what I ment that there is no logic behind improved milage after 1st service as they just wash away the car  and give you back.

Reg changing of oil again I will relate to the engine life & not with improved milage after 1st service.

BTW the best milage I have got(23.7km/ltr) as of now is during my runin period & after that am still struggling to achive the same .

Master : FE depends a lot on the driving speed. Usually as a caution for proper breakin we maintain optimum speeds so we get better FE. Later we tend to drive with higher speed/rpm resulting in lower FE. Check your tyre pressue and fix the frequency for air fill.

In my case initially when I did a tankful check maintaining 80 - 100 kms speed (mostly at 2000 rpm) I got 22 kpl. Then when I did the same run at higher rpm and 120 - 150 kms speed (around 3K rpm)I got about 14kpl.

Maintaining rpm at and between 1500 - 2000 gives the best FE as far as i20 crdi is concerned.

@arun: We are not discussing better fuel effciency. We are discussing here where people say" FE SHOULD BE BETTER AFTER FIRST SERVICE"