sand-eel
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Right I've been thinking about this, people say lots of short journeys wears the engine faster than lots of long journeys.
I was thinking how? because if say your short journey was 2 miles and the long journey was 10 miles, the 10 miles journey still has to go through the 2 miles mark and on both journeys the oil/ water temp will still be the same, so should be wearing the same upto 2 miles.
Anyone have any theories?
[Edited on 24-02-2009 by sand-eel]
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deano87
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Less than 2 miles is bad 
It basically goes on the theory the oil isn't at operating temperature when the engine is first started therefore not protecting the engine as a whole. That is what I gathered anyway. . .
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mazdaspeed
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2miles isnt really a short journey, I think most people associate short as being down the road to the shops. In 2 miles most cars would be upto normal temperature unless its winter.
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antnee
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To do with temps basically. I can drive for 10miles before my oil is upto 90deg. Sometimes it takes 2-3 miles for coolant to get to 90 too!
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Colin
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Its basic mechanical principles, running for longer at constant speed produces less wear than a similar amount of distance at varying speeds & for short intervals.
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antnee
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quote:
Originally posted by mazdaspeed
2miles isnt really a short journey, I think most people associate short as being down the road to the shops. In 2 miles most cars would be upto normal temperature unless its winter.
2miles is short
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Colin
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2 miles the cars probably just getting up to temperature.
This is the exact reason Im weary of '1 lady owner, low mileage' cars. Ok its done 30k miles but dos that mean in 2nd gear starting & stopping all the way a mile or so to work & back!!
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sand-eel
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yeah but on the long and short jouneys that oil temp would be the same at the end of the short journey to the same point on the long journey, If you know what i mean?
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mazdaspeed
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Why do you warm up a car to drain the oil?
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DaveyLC
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There are cars with intergalactic motorway miles that have spent their lives just wafting around... Same with cars with auto transmissions: less wear on the engine in general as the crank speed tends to stay in a certain range.
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antnee
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quote:
Originally posted by sand-eel
yeah but on the long and short jouneys that oil temp would be the same at the end of the short journey to the same point on the long journey, If you know what i mean?
yes but the oil is warming up, thus lubricating the engine better, thus less wear on the internals
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sand-eel
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less wear when heated up yes, but it still has to heat up so will have the same wear at the start everytime until heated up
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Nic Barnes
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i see what your saying or getting at.
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sand-eel
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thank god, its hard to explain really.
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sand-eel
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I think its a government conspiracy, so people take the bus instead
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Nic Barnes
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quote:
Originally posted by sand-eel
thank god, its hard to explain really.
what you are saying i think is....
short journey car warms up to x degrees of oil and water and tranny fluids etc. on long journey it still has to warm up to that point aswell.......
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Mike
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quote:
Originally posted by sand-eel
less wear when heated up yes, but it still has to heat up so will have the same wear at the start everytime until heated up
Basically, a journey of 20miles is better than 10 journeys of 2 miles, because once the engine is upto temp there is a lot less wear for the remaining mileage of the long journey but with the short journeys the engine would never really get upto temperature properly and therefore wear would be worse.
It's more an argument for when you've got one car which has 100k on the clock which has lived on the motorway all it's life compared to a car with say 40k on the clock which some old woman has drove to the shop 5 mins down the road and back again and that's all it's ever been used for. Realistically the 100k motorway car would quite possibly have less engine wear
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sand-eel
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quote:
Originally posted by Nic Barnes
quote:
Originally posted by sand-eel
thank god, its hard to explain really.
what you are saying i think is....
short journey car warms up to x degrees of oil and water and tranny fluids etc. on long journey it still has to warm up to that point aswell.......
EXACTLY
So in theory should have the same wear to that point.
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Mike
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quote:
Originally posted by sand-eel
quote:
Originally posted by Nic Barnes
quote:
Originally posted by sand-eel
thank god, its hard to explain really.
what you are saying i think is....
short journey car warms up to x degrees of oil and water and tranny fluids etc. on long journey it still has to warm up to that point aswell.......
EXACTLY
So in theory should have the same wear to that point.
It's after that point were it counts tho, the long journey is still in it's early stages, whereas the short journey has ended and the car is now going to cool down again before doing another short journey later where it will have all the early wear again
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Ren
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I see it like this.
20 miles in one drive is easier on the engine than 20 single mile drives... I think the damage is supposed to be sustained over long term periods if you understand me.
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sand-eel
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but the long journey car will cool down and have early wear again when it does another journey.
Lets put it this way 
cold car = 2 wear points per mile
hot car = 1 wear points per mile
so a 2 mile journey = 4 wears points
10 mile journey = 12 wear points
as it still goes through 2 miles and gets 4 wear points but has the extra 8 miles adding 8 wear points so 12 wear points.
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Nic Barnes
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but if the oil never gets up to temperature properly ever, it wears stuff out. thats just the way it is.
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sand-eel
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I think i'll just leave this 
It's just that a long journey car will always go through what a short car journey will do every time.
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Ren
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Registered: 16th Oct 04
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quote:
Originally posted by sand-eel
but the long journey car will cool down and have early wear again when it does another journey.
Lets put it this way
cold car = 2 wear points per mile
hot car = 1 wear points per mile
so a 2 mile journey = 4 wears points
10 mile journey = 12 wear points
as it still goes through 2 miles and gets 4 wear points but has the extra 8 miles adding 8 wear points so 12 wear points.
Yes but the 10 mile car has done 8 extra miles... The cold start car needs to do 10 miles before you compare them.
Put it this way, if you're going per mile then it makes a difference. Using your method, lets say you buy a new car and do 1000 miles in it in one journey, and lets just assume that it takes the car 2 miles to warm up. (So thats 4 points + 998 = 1002 wear points)
Now lets say you spread the 1000 miles over 1000 days (one mile per day), which would equal 2000 wear points in total as the engine never warms up.
Compare the two engines, and even though they've both done the same amount of miles, one is more worn than the other.
[Edited on 25-02-2009 by Ren]
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sand-eel
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quote:
Originally posted by Ren
quote:
Originally posted by sand-eel
but the long journey car will cool down and have early wear again when it does another journey.
Lets put it this way
cold car = 2 wear points per mile
hot car = 1 wear points per mile
so a 2 mile journey = 4 wears points
10 mile journey = 12 wear points
as it still goes through 2 miles and gets 4 wear points but has the extra 8 miles adding 8 wear points so 12 wear points.
But if you're going per mile then it makes a difference. Using your method, lets say you buy a new car and do 1000 miles in it in one journey, and lets just assume that it takes the car 2 miles to warm up. (So thats 4 points + 998 = 1002 wear points)
Now lets say you spread the 1000 miles over 1000 days (one mile per day), which would equal 2000 wear points in total as the engine never warms up.
Compare the two engines, and even though they've both done the same amount of miles, one is more worn than the other.
I get it now 
I think I was over complicating it for some reason.
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