There's an amazing difference in gas mileage between long and short trips

[JohnCU]

Originally posted by: mercanucaribe
Driving .4 miles is bad because the engine never gets a chance to warm up. In a week, you've driven 4 miles on a cold engine.

I thought all the roads in NYC had sidewalks.

maybe i'm missing something, but let's say you drive 5 miles everyday to work. let's say it takes 2 miles for the engine to warm up. that's 25 miles a week, 10 of which are cold. you can't avoid driving cold at the start so what am i missing?

 

[BD2003]

Originally posted by: JohnCU

Originally posted by: mercanucaribe
Driving .4 miles is bad because the engine never gets a chance to warm up. In a week, you've driven 4 miles on a cold engine.

I thought all the roads in NYC had sidewalks.

maybe i'm missing something, but let's say you drive 5 miles everyday to work. let's say it takes 2 miles for the engine to warm up. that's 25 miles a week, 10 of which are cold. you can't avoid driving cold at the start so what am i missing?

Nothing really. There is a factor that when the engine rarely gets enough oil flowing, that it will lead to proportionately more damage than if it has been driven longer, but primarly, in the end, for the equivalent amount of miles on the odometer, the engine will have a LOT more wear than one that was driven further more frequently..

 

[Chaotic42]

Originally posted by: BD2003
Nothing really. There is a factor that when the engine rarely gets enough oil flowing, that it will lead to proportionately more damage than if it has been driven longer, but primarly, in the end, for the equivalent amount of miles on the odometer, the engine will have a LOT more wear than one that was driven further more frequently..

Right, but I wouldn't have any more damage over a one month period of these trips than I would over a one month period of 20 mile trips, correct?

 

[mercanucaribe]

Originally posted by: JohnCU

Originally posted by: mercanucaribe
Driving .4 miles is bad because the engine never gets a chance to warm up. In a week, you've driven 4 miles on a cold engine.

I thought all the roads in NYC had sidewalks.

maybe i'm missing something, but let's say you drive 5 miles everyday to work. let's say it takes 2 miles for the engine to warm up. that's 25 miles a week, 10 of which are cold. you can't avoid driving cold at the start so what am i missing?

I see what you're saying, but I think it's better for the engine to be warmed up and lubricated in between the short cold trips, instead of going for a whole week without warming.

 

[iamwiz82]

Originally posted by: Chaotic42

Originally posted by: BD2003
Nothing really. There is a factor that when the engine rarely gets enough oil flowing, that it will lead to proportionately more damage than if it has been driven longer, but primarly, in the end, for the equivalent amount of miles on the odometer, the engine will have a LOT more wear than one that was driven further more frequently..

Right, but I wouldn't have any more damage over a one month period of these trips than I would over a one month period of 20 mile trips, correct?

Your oil will break down faster. I just changed the oil on both of our cars and my wife's oil in 6 months was head and shoulders above the oil in my truck that was 2 months old. Also you have to consider other parts of your car. Muffler will rot out faster, transmission will probably shift more and with cold fluid, etc.

 

[Chaotic42]

Originally posted by: iamwiz82
Your oil will break down faster. I just changed the oil on both of our cars and my wife's oil in 6 months was head and shoulders above the oil in my truck that was 2 months old. Also you have to consider other parts of your car. Muffler will rot out faster, transmission will probably shift more and with cold fluid, etc.

Well, assuming that I did walk to work everyday, the car would just sit up for days at a time. Wouldn't that be even worse?

 

[BD2003]

Originally posted by: Chaotic42

Originally posted by: iamwiz82
Your oil will break down faster. I just changed the oil on both of our cars and my wife's oil in 6 months was head and shoulders above the oil in my truck that was 2 months old. Also you have to consider other parts of your car. Muffler will rot out faster, transmission will probably shift more and with cold fluid, etc.

Well, assuming that I did walk to work everyday, the car would just sit up for days at a time. Wouldn't that be even worse?

No, it would be much better.

The reason a cold engine wears out so fast is because there is little to no lubrication and protection. There is essentially metal rubbing against metal, all spinning violently due to explosions. It takes time for the oil to warm up and coat everything.

Leaving the car sitting, theres no real damage caused by the moving parts, because well...theyre not moving.

 

[oboeguy]

There's something wrong with you if you drive .4 miles. That's eight city blocks, so eight minutes of walking.

 

[Chaotic42]

Originally posted by: oboeguy
There's something wrong with you if you drive .4 miles. That's eight city blocks, so eight minutes of walking.

Again, it's not really .4 miles.

 

[DrPizza]

Originally posted by: Chaotic42

Originally posted by: BD2003
Nothing really. There is a factor that when the engine rarely gets enough oil flowing, that it will lead to proportionately more damage than if it has been driven longer, but primarly, in the end, for the equivalent amount of miles on the odometer, the engine will have a LOT more wear than one that was driven further more frequently..

Right, but I wouldn't have any more damage over a one month period of these trips than I would over a one month period of 20 mile trips, correct?

One of the products of combustion is water. If your muffler is cold, some of it condenses in there. Unless it heats up and drives out that water, you're going to rot out the muffler a lot sooner.

 

[secretanchitman]

also got a reality check just on monday/tuesday. my parents drove to detroit, MI from chicago, IL using their mercedes-benz ML500 (gas guzzler, honestly), probably using the highway mostly. there was 263 miles left to drive, and i usually use the ML500 going to/from school. at the end of tuesday only driving to/from school (5-10 minutes each way going the speed limits), the mileage was 175 miles left to drive.

god, that car/suv gets extremely bad city mpg, but average highway mpg. thats probably why i got poor mileage.

 

[Vic]

Originally posted by: Chaotic42
So it really works out for the better if I drive. I have the gym for exercise.

*pfft* my gym is almost a mile from my house and I almost always walk there on dry days.

As has been stated numerous times, you should drive your car such a short distance. It's not just the cold miles, it's that the engine never even gets warm that does the most damage. Sludge city!