is extremely low mileage bad

June 29, 2008 10:12 AM

A friend has a 10-year old Lexus (with only ~50k miles on it!) that gets driven 2-4 miles per week. Is there any harm in this? (It is a second car for one person.) Oil would keep recirculating due to the weekly drive and the alternator should keep the battery charged. Right? I mean, if the car is fueled only once every 12-18 months can that be good for it? (sediment?) Would any other problems be likely?
posted by umlaut to travel & transportation (13 answers total)

Gasoline can last quite a while, but sedimentation can occur and will eventually cause some issues. Instead of putting a full tank in every 12-18 months, just "fill up" from a five-gallon gas can and keep the car itself hovering near empty.
posted by sonic meat machine at 10:20 AM on June 29, 2008

I have a 7-year old Hyundai with about 18600 miles on it which I use about thrice a week. Works fine with and has never given me any problems. Just a couple of months ago, I did a 1400 kilometre road trip in it and my car did wonderfully well... Not sure about the irregular fueling-up, I refuel my car every two weeks or so.
posted by cyanide at 10:22 AM on June 29, 2008

It is unlikely to harm the car in any real sense, but it is certainly not the best thing in any way. It will not be functioning at its best by any means. 2-4 miles per week is a ridiculously short journey for a car as it will not be fully warmed up and will be constantly running at an inefficient fueling level. The lack of full heat cycles will allow engine deposits to form ('coking up' or carbon deposits in the combustion chamber) and as these build up that will also ultimately harm performance and efficiency, but will not necessarily damage it, per se.

Keeping the fuel level low (and hence more frequent fueling) will be better for it, as this will reduce the chance of sedimentation forming, but you really have to question the validity of needing a second car to go such a ludicrously short distance.

It is possible that the short journey may not fully charge the battery, but only if one or other becomes defective. A solar trickle charger on the dash would fix that for the times it is inactive.

if the oil is changed every other year (if it is synthetic) then it will be fine. In fact, it will probably be fine if it is left even longer than that. The small usage of the vehicle makes it unlikely that high wear will result from less than optimum oil.

But the question remains as to what on earth this vehicle does that justifies its continued use? 2-4 miles a week? A second car for one person?

Sell it and find an alternative, surely. A weekly taxi ride would be cheaper than the cost of ownership of a car like that.
posted by Brockles at 10:26 AM on June 29, 2008 [3 favorites]

I don't know if it is a problem these days, but my grandmother used to go through a lot of mufflers because her short & infrequent driving never gave her exhaust system enough time to heat up and evaporate off all the water that would condense in the first few minutes of driving.
posted by Good Brain at 10:27 AM on June 29, 2008

The worst problem is the oil doesn't get heated up enough to drive off moisture, unburnt fuel and combustion nasties that gets past the rings. This can thin out the oil considerably and cause rusting of stuff like the oil pan.

If it was me I'd still change the oil every three months and every month or so I'd take the car on a long enough drive that the engine fully warmed up.

Not a concern with newer cars that have sealed gas systems but on cars that had tanks that vented to the atmosphere gas would collect moisture and rust the tanks out.
posted by Mitheral at 10:54 AM on June 29, 2008

From at least small engine experience old (1+year) gas can definitely bolix up an engine (no permanent harm done); not filling the tank to get that down to a few months between would probably make sense. I don't know about the other factors being discussed.
posted by nanojath at 11:43 AM on June 29, 2008

The easy answer is just to drive it for ten minutes extra every week or so. It might also be a good idea to start it and let it run every few days or so, even if it doesn't get driven.
posted by iknowizbirfmark at 12:08 PM on June 29, 2008

My 8 year old Passat only has 21K miles on it (this floors my friends in LA where I grew up for obvious reasons). My mechanic told me to fill the gas tank when it gets to the half-way mark just to keep the gas "fresh."
posted by Taken Outtacontext at 12:50 PM on June 29, 2008

I had to replace the exhaust system in my previous car because it rusted out due to lack of use. It never got hot enough to clear out the moisture. After that, I took it out for a "run" once a week on the highway. The car is still on the road and is 21 years old. So, if you don't want to replace the exhaust system or deal with the above, take it out every week or so, according to my mechanic.
posted by acoutu at 1:52 PM on June 29, 2008

nthing condensation in the exhaust as the biggest problem.

The oil filters and oil should be changed regularly too (check the car service schedule, but probably every 3 or 6 months).
posted by zippy at 2:36 PM on June 29, 2008

I often hear extreme paranoia over oil changes on here. It is usually totally overstated. Use of a fully synthetic oil in a car with that little use will not require it being changed any more often than 18 months to two years. Synthetic oil has no particular shelf life like mineral oil has, and the tiny, miniscule amount of wear generated by the use pattern means that 3-6 months is utter overkill, and the oil will hardly look any different from when it came out of the can.

Even with a non-synthetic oil, any suggested service interval of less than 12 months has no merit either, in this application. Oil simply doesn't degrade that fast without high loads and mileage.
posted by Brockles at 2:48 PM on June 29, 2008

Brockles, makes a good point - that the engine is not getting heavy use. Normally, it's cars under severe load (off-road trucks, taxis) where the manufacturer specifies a more frequent oil-change schedule.

There's another angle to this car, though.

I think the issue here is not the oil breaking down, but the engine accumulating crud through operation and oxidation.While this engine is not heavily used, unlike a completely unused engine, this one is going through partial thermal cycling every week - enough of a temperature change to cause condensation, not enough to cause the water to evaporate - I suspect this engine will have more moisture internally than a crated, unused engine.

This is only a guess, though.
posted by zippy at 11:10 AM on June 30, 2008

The small amount of use on a very regular basis (once a week is by no means infrequent use of a car) would only produce a small amount of condensation, though. Yes, a proper warming every month would help, but an engine that gets oil soaked once a week is unlikely to start to corrode internally to any degree. Burning off the condensation is always a good thing, though - the exhaust point is a very good one.
posted by Brockles at 11:43 AM on June 30, 2008