Engine wear & don't do long journeys - what is the logic?
Discussion
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?
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
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).
Edited to add: Assuming same car/age in my example above
Edited to add: Assuming same car/age in my example above
Edited by Targarama on Wednesday 20th October 17:13
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?
Imagine two identical cars, one owned by an estate agent, one by a sales rep.
In one year, both cover 50k miles.
the estate agent is doing hundreds of short, local journeys. His car is being started from cold, run and turned off while still not at optimal temperature for the oil to work.
the sales rep goes up and down motorways, cruising at 70-80mph. The car spends 99% of its time at optimal temps.
Car 1 will suffer far more wear than car 2.
In one year, both cover 50k miles.
the estate agent is doing hundreds of short, local journeys. His car is being started from cold, run and turned off while still not at optimal temperature for the oil to work.
the sales rep goes up and down motorways, cruising at 70-80mph. The car spends 99% of its time at optimal temps.
Car 1 will suffer far more wear than car 2.
It's driving an engine with cold oil that ruins it. If one guy lives 10 minutes from work and the other an hour, then the former car will spend 100% of its life running on cold oil, where the other car wil only spend a sixth of its life on cold oil. So even if the first guy's car has a lower mileage, it may have been subjected to more engine wear than the second guy's car. For example, if car 2 has 60,000 miles, 10,000 miles is on cold oil. If car 1 has just 30,000 miles on the clock, 30,000 miles are on cold oil so it has far more engine wear despite being lower mileage...
Edited by RobM77 on Wednesday 20th October 17:35
EK993 said:
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?
The true comparison is person x does 4 x 15 min journeys to person Y doing 1 x 1 hour journey. Same distance but X gets more wear.
Fuel enrichment at start up is one reason short journeys cause more wear.
When cold some of the excess fuel will mix with the oil. If you drive for long enough the engine heat will evaporate the fuel and not cause a problem, if it stays in the oil the diluted oil won't protect the engine as well and therefore accelerate the wear.
It's typical of pensioners cars who only potter a few miles to the shops never letting the car warm up fully. The oil can end up so diluted it rises up the dipstick and will stink of the fuel.
If it's fully warmed up then there's no issue.
Wear mainly comes from the initial cold start, if you do a lot of cold starts then there will be more wear. If you don't let the car fully get to temperature between cold starts this will accelerate wear (and rust out the exhaust, gum up the valves etc. etc.).
When cold some of the excess fuel will mix with the oil. If you drive for long enough the engine heat will evaporate the fuel and not cause a problem, if it stays in the oil the diluted oil won't protect the engine as well and therefore accelerate the wear.
It's typical of pensioners cars who only potter a few miles to the shops never letting the car warm up fully. The oil can end up so diluted it rises up the dipstick and will stink of the fuel.
If it's fully warmed up then there's no issue.
Wear mainly comes from the initial cold start, if you do a lot of cold starts then there will be more wear. If you don't let the car fully get to temperature between cold starts this will accelerate wear (and rust out the exhaust, gum up the valves etc. etc.).
I see the OPs point of view totally and agree with it too.
Both cars are run from cold for those 15 minutes to the same temperature. If you turn off car A after those 15 minutes and let it cool, why will it wear the engine more than a car that then continues to run for another 45minutes?
That extra running doesn't reverse the wear the engine suffered in the first 15 minutes it was cold.
Both cars are run from cold for those 15 minutes to the same temperature. If you turn off car A after those 15 minutes and let it cool, why will it wear the engine more than a car that then continues to run for another 45minutes?
That extra running doesn't reverse the wear the engine suffered in the first 15 minutes it was cold.
Deluded said:
I see the OPs point of view totally and agree with it too.
Both cars are run from cold for those 15 minutes to the same temperature. If you turn off car A after those 15 minutes and let it cool, why will it wear the engine more than a car that then continues to run for another 45minutes?
That extra running doesn't reverse the wear the engine suffered in the first 15 minutes it was cold.
Well, obviously it does not reverse the wear. The point that's being missed is that short journeys from cold contribute more wear per mile covered than long ones at optimum temperature. Both cars are run from cold for those 15 minutes to the same temperature. If you turn off car A after those 15 minutes and let it cool, why will it wear the engine more than a car that then continues to run for another 45minutes?
That extra running doesn't reverse the wear the engine suffered in the first 15 minutes it was cold.
It's blindingly obvious that driving for a further 45mins wears the engine more than stopping after 15, but it's equally apparent that the fair comparison is between four 15-minute trips (or 8x4 miles, if you like) and one one-hour one (of 32 miles). As above
I have just read this thread and logic is not always right.
Me and one of my work colleagues have the exact same car, same age, same engine, same model. Only difference is his is lower mileage by around 35k.
I do a 15 minute drive for work everyday and he does a 1 and half hour drive everyday.
I have never had any issues/problems with my car. Runs spot on everytime. I service it once every 6 months.
His car is always going wrong suspension, brakes, cv boots, engine management light comes on at least once every couple months, he services his car every 5-6 months, he has broken down 7-8 times in the last year and half.
So logic of longer drives do less damage is not always correct and I think that it proves it there with me and my work colleague.
Me and one of my work colleagues have the exact same car, same age, same engine, same model. Only difference is his is lower mileage by around 35k.
I do a 15 minute drive for work everyday and he does a 1 and half hour drive everyday.
I have never had any issues/problems with my car. Runs spot on everytime. I service it once every 6 months.
His car is always going wrong suspension, brakes, cv boots, engine management light comes on at least once every couple months, he services his car every 5-6 months, he has broken down 7-8 times in the last year and half.
So logic of longer drives do less damage is not always correct and I think that it proves it there with me and my work colleague.
Deluded said:
I see the OPs point of view totally and agree with it too.
Both cars are run from cold for those 15 minutes to the same temperature. If you turn off car A after those 15 minutes and let it cool, why will it wear the engine more than a car that then continues to run for another 45minutes?
That extra running doesn't reverse the wear the engine suffered in the first 15 minutes it was cold.
If the car never fully warms up, the exhaust will rot out quickly due to condensation xollecting in the muffler(s).Both cars are run from cold for those 15 minutes to the same temperature. If you turn off car A after those 15 minutes and let it cool, why will it wear the engine more than a car that then continues to run for another 45minutes?
That extra running doesn't reverse the wear the engine suffered in the first 15 minutes it was cold.
Also if the oil is never fully waemwd up, it xan get contaminated with fuel and/or condensation.
In other words 10 x 5 minute trips may well do more damage than 10 x 30 minutes.
In winter my car hasn't fully warmed up until about 20 minutes into the morning commute.
But longer journeys with what happens with my work colleagues car as he drives a dam site longer than me and he has a lot more problems with the car than me. I only ever do short journeys the longest drive I have done in the car since owning it which is 2 years now is around a 45 minute drive. Both cars are serviced regularly and the one that does long journeys has a lot more issues than my car that only ever does short journeys. So the theory of long journeys is better for a car is not always correct.
People say motorway miles are best for a car but they are hard miles on the car coz it's being revved at a constant rpm for long periods of time. It's like if you work yourself hard for a hour your more tired out than someone who has taken it easy for a hour. Gos a very similar way for engines as well.
People say motorway miles are best for a car but they are hard miles on the car coz it's being revved at a constant rpm for long periods of time. It's like if you work yourself hard for a hour your more tired out than someone who has taken it easy for a hour. Gos a very similar way for engines as well.
Gassing Station | General Gassing | Top of Page | What's New | My Stuff