Engine wear & don't do long journeys - what is the logic?

[EK993]

Was reading a thread today that got me thinking.. someone asked about how to best preserve the engine to make sure they don't lose HP over the years... one of the responses was don't do short journeys as it increases engine wear.

Now, in theory this makes sense in my head.. however, isn't the engine wear exactly the same? Eg if I do a 15 minute drive to the office every day I cause X amount of wear.

So lets say instead of a 15 minute drive I have an hour drive - during the first 15 mins of driving I have caused exactly the same wear as my first example above - I then have additional wear for the extra 45 mins I have been driving. So why do short drives cause MORE wear as nothing changes during the first 15 mins regardless of how much further you drive after that?

Edited by EK993 on Wednesday 20th October 17:12

[EK993]

Targarama said:

That doesn't make sense. A 100k car that has done lots of short journeys will be more worn than one that has done 200 mile motorway journies. Firstly most wear occurs when cold and secondly cruising a long distance doesn't use the brakes, clutch or even the suspension much (less potholes and corners on motorways).

Agreed engine wear occurs when cold - but in my example driving for either 15 mins or an hour, the engine is equally cold for the first 15 minutes for both journeys and has caused exactly the same wear.

If peson x does a year of 15 minute journeys every day, and person y does a year of 1 hour journeys every day then surely person y has more wear?