Maintaining lightly used car -- idle 10 minutes/week?

[Muse]

~6 months out of the year (in recent past, anyway), I've sometimes left my 1997 Mazda 626LX 4cylinder 4.0L coupe sitting unused in the driveway for up to 6 weeks with no attention other than a little Harbor Freight 500ma charger keeping the battery over 12.5v (I also have a Schumacher 1.5amp charger, am contemplating getting their 3amp charger).

Yesterday I had the car smogged (it's only at ~27,000, but the DMV wanted it done at a Star station, for whatever reason... the guy said they can do this randomly), and the guy says that they recommend for lightly used cars to idle them for ~10 minutes a week. Is this a good idea?

 

[Lean L]

Well yes, you want the liquids to move around a bit and the engine to run.

Best to just drive it a few miles a week. The tires will be gone after a while if you just leave them sitting on the same tread forever, the brakes will form a thicker layer of rust if you don't grind them a little, and the transmission will also need some movement.

It's best to go through all of the gasoline in that car probably twice a year so maybe don't fill it all the way up if you can't burn it all in that time. Otherwise, you should treat the gasoline with maintainer.

 

[Ferzerp]

No, it isn't a good idea. Just idling an engine and never letting it get to operating temperature is a huge mistake.

Just drive the thing ever week or two as the above person said.

 

[boomerang]

Just to add, you should change the oil yearly. You'll find that information in your owners manual. The way your car is driven you can't base oil changes on the amount of miles you put on it.

 

[Meghan54]

I'd also suggest, in addition to simply driving the vehicle a few miles every month, is to add a fuel stabilizer to your fuel load. If you're undoubtedly using ethanol-laced gas, the ethanol can and will oxidize fairly rapidly, like within 2-3 months, leaving lower octane fuel that can cause hard starting, poor running, possibly gum and varnish formation. This is probably the root of most of the small outdoor engine problems....leaving gas stored incorrectly (no stabilizer) in both the gas tank and gas can.

 

[pauldun170]

After sharing stories of carb issues (Motorcycles) after ethanol replaced mtbe, coworker recomended http://mystarbrite.com/startron/ as an alternative to stabil.

 

[tortillasoup]

Driving a vehicle once a month is fine if you put a battery tender on the battery. DO NOT IDLE THE VEHICLE. Spark plugs never get hot enough to burn off the carbon along with getting rid of moisture in the oil, etc. etc. You want to drive the vehicle, a nice long cruise at continuous speed whether or no the highway or what ever for at least 20 miles, getting everything hot and flowing well.

IF you just idle the vehicle, you'll give that car lawnmower syndrome and basically kill it.

The reason you want to drive on the highway/cruise is that it gets the oil hot but at the same time, the fuel mixture is lean so any fuel/moisture that gets dissolved into the oil has a chance to evaporate and burn in the combustion chamber. The engine coolant temperature will come up first and then some time later the oil will achieve the operating temperature of 180F+. A lot of idling/stop and go traffic means rich fuel mixtures which will pollute the oil which is the opposite of what you want. Don't assume that if the engine achieves operating coolant temperature that the oil has as well because it hasn't!

 

[TridenT]

I'd also suggest, in addition to simply driving the vehicle a few miles every month, is to add a fuel stabilizer to your fuel load. If you're undoubtedly using ethanol-laced gas, the ethanol can and will oxidize fairly rapidly, like within 2-3 months, leaving lower octane fuel that can cause hard starting, poor running, possibly gum and varnish formation. This is probably the root of most of the small outdoor engine problems....leaving gas stored incorrectly (no stabilizer) in both the gas tank and gas can.

This. Add fuel stabilizer.

Jay Leno might have some more tips for you...

 

[desy]

I'd take it out once a month 20-30 min
I wouldn't idle for 10 minutes once a week

 

[phucheneh]

Did it fail smog or not?

There are two different things to think about here:

1) Cars that see very light use with very tame drivers are the most susceptible to things like carbon buildup. When I get in a car, punch the gas a little (while going down the road), and am rewarded with that lovely 'jar of marbles' spark knock noise, it is always on a car that is driven for short periods, and I'm guessing they never see more than 1/4 throttle. This is where you find legitimacy to the old 'Italian tune-up' joke (as in, beat the snot out of it a little bit and it'll run better).

But that's cars that are still DRIVEN regularly...just for small amounts, and again, with a light foot.

2) Cars that just sit parked a lot. I would argue that idling them once a week or some such, even for just a few minutes, is beneficial. Get fluids circulating, get the belts turning, ect. Mechanical devices that sit in one position generally become...less mechanical.

But driving it would be much better for it. Get it up to temp and give it the business. A few hard pulls, a few hard stops, will do a lot to keep things functioning properly. But don't be one of those naive people that things an undriven car doesn't need maintenance. Your car still subscribes to that whole 'entropy' thing.

 

[MongGrel]

Blow that carbon out !!!!

J/K a bit, but most things been covered it looks, was guilty of having a Jeep Cherokee that didn't get driving enough for awhile, finally sold that off and took a little retro work on it.

 

[BUTCH1]

Driving a vehicle once a month is fine if you put a battery tender on the battery. DO NOT IDLE THE VEHICLE. Spark plugs never get hot enough to burn off the carbon along with getting rid of moisture in the oil, etc. etc. You want to drive the vehicle, a nice long cruise at continuous speed whether or no the highway or what ever for at least 20 miles, getting everything hot and flowing well.

IF you just idle the vehicle, you'll give that car lawnmower syndrome and basically kill it.

The reason you want to drive on the highway/cruise is that it gets the oil hot but at the same time, the fuel mixture is lean so any fuel/moisture that gets dissolved into the oil has a chance to evaporate and burn in the combustion chamber. The engine coolant temperature will come up first and then some time later the oil will achieve the operating temperature of 180F+. A lot of idling/stop and go traffic means rich fuel mixtures which will pollute the oil which is the opposite of what you want. Don't assume that if the engine achieves operating coolant temperature that the oil has as well because it hasn't!

I don't think highway or city would make much difference as long as the oil has a chance to come up to operating temps and stay that way for a good 10-15 minutes, this will eliminate any condensation in the sump. Today's engines are so tightly controlled I'm not thinking stop and go will "pollute" the oil, a steady 75 on the highway would be best but lets face facts, most cars are operated in a city driving situation, when it's cold the PCM will compensate with a longer pulse width on the injectors (the same effect as a "choke" on a carb'ed engine) and bump up the idle a few hundred RPM until "closed loop" operation takes place, (the O2 sensors are hot enough), slightly higher idle speed is normal until the PCM senses coolant temp starting to rise. My Mom's in this exact situation right now, she just started living in an assisted living facility but we don't trust her to drive her car (13 Corolla) only has 4K miles on it, after it sat 6 weeks I put a full bottle of Sta-bil in the tank but I need to get the oil changed, it's still the factory oil and it's coming up on 1 year of service, I'll probably do it next week.

 

[tortillasoup]

Cars that are driven exclusively in city driving, even for today's vehicles will not live a very long life. The only exception to this would probably/hopefully be a hybrid vehicle as on the Toyota Prius, the engine is considered "fully warmed up" when it reaches a relatively cold 160F. When I say fully warmed up, it means that it will shut the engine off and use the electric motors when cruising at low speed or stopped at a stoplight.

 

[Zenmervolt]

Cars that are driven exclusively in city driving, even for today's vehicles will not live a very long life.

That is due to the increased short-trip usage, not to the low speeds or idling. And NYC taxis routinely go 300,000 miles or more, which is not exactly a "short" lifespan.

It takes a good 20-30 minutes for the oil to get up to temp and cars used exclusively in cities often never run that long. Also, city exclusive driving tends to mean longer hours but fewer miles, so the mileage appears artificially low for the car's lifespan even though the actual running time is longer than for a highway-driven car.

As far as "running rich" at low speeds, no. Just no. That's not how EFI works. Once the engine is in closed-loop mode, it's not running any richer at idle than it is under load. In fact, it's probably slightly leaner at idle because there's no load on the engine and therefore the EFI isn't going to be adding any enrichment to compensate for engine load.

Modern (by which I mean anything from about 1980 forward) liquid-cooled engines are very, very, very good at maintaining thermal equilibrium as long as the cooling system is in proper order. Sitting at idle will not cause the engine to run cooler than it would driving down the road. In fact, at speeds above about 25 mph there is far more airflow over the radiator from the vehicle's motion than the fans could ever hope to move with the car sitting still; the cooling system wants to run HOTTER at idle and unless it's in good shape, the engine's equilibrium coolant temperature at idle will be higher than the temperature when it's running down the road. While the engine itself is making slightly less heat at idle, the ability of the cooling system to expel that heat is vastly diminished with the vehicle sitting still and without perfectly functioning radiator fans and a clean cooling system an engine will tend to run very slightly hotter at idle.

What is a problem with just starting a car and letting it idle is that it takes the engine longer to come up to operating temperature, which means more time in open-loop operation. Instead of 20-30 minutes of driving, it may take 30-40 minutes of idling to get the oil fully up to temperature and most people don't let a car sit and idle that long. Plus, unlike slow speeds or warm idling, open-loop operation does run richer, which can lead to carbon buildup.

Overall, the best thing for the OP is to take the car out and drive it for about 20 minutes. City, highway, rural doesn't really matter.

ZV

 

[BUTCH1]

Good points ZV, I would add one small tidbit in that some cars in the '80-'84 span used the dreaded "feedback carb's", there was an O2 sensor but FI had not yet been introduced or was too expensive to use at the time, instead was the practice of using the primitive PCM to adjust the metering rods inside the carb's, it was plagued with issues for many cars GM's was specially bad, my '82 Cutlass had one, it started the classic signs when it went bad, black, sooty exhaust plumes. Not want to tackle a rebuild on one of these beasts I called for a price on a re-manufactured one, $500!, I then ordered the kit and rebuilt it but it never really ran right with the computer hooked up to it so I unplugged it and ran it like that for the rest of the time I had the car.

 

[bononos]

Getting a flat spot on the tires would be a worry. I would push a it few inches every few days.

 

[Zenmervolt]

Getting a flat spot on the tires would be a worry. I would push a it few inches every few days.

Radial tires don't flat spot nearly as much as the old bias-ply tires did. As long as the car moves every month or two it'll be fine. Modern tires with proper air pressure take several months to develop permanent flat spots; the six-week intervals the OP is talking about are just not long enough for flat spots to be a legitimate worry as long as the tires are properly inflated.

If the tires go flat while the car sits, that's a different matter.

ZV

 

[Muse]

Did it fail smog or not?

The car passed smog handily.

Overall, the best thing for the OP is to take the car out and drive it for about 20 minutes. City, highway, rural doesn't really matter.

ZV

Actually, in recent years during the winter, unless I'm making a Costco run (~6 miles each way, 1/2 on the highway), I may not do anything with the car except for a trip every week or two to the golf course to hit some range balls and putt. That trip is about 5 miles each way. However, it's up hill. The last mile or so is a climb of about 1000 feet, the whole 5 mile ride to the course is a rise in elevation of around 1100-1200 feet, a pretty steep climb (tough on a bicycle!) near the end. So, the engine and oil are (I figure) going to be pretty worked up in temperature by the time I get to the course. The return trip (1.5 hours later on average) is basically a decent, the brakes get a workout (I put the car in second gear to save the brakes, but I'm sure any rust is ground off). Each way, the trip takes around 15 minutes on average, I think. The drive is through town except for the big elevation change, when it's just a climb into the hills, only one light and it's almost always green.

Does this sound like it's enough to burn water out of the oil? Should I use Stabil or similar fuel additive? Should I take the car on longer rides?

My mechanic years ago told me that for a seldom used car he would keep the fuel tank as full as practical to reduce the air in the tank, which would reduce the effect of water condensing into the gas and contaminating the oil. Therefore, when I go to Costco (I do this every ~8 weeks on average) I always fill the tank, even if it's only down a few gallons.

He also recommended detaching the battery cables, and I used to do that with my other car, but now I just use a trickle charger when I don't drive much.

He also recommended using 100% synthetic oil, if I wasn't going to do regular oil changes. Every 6 months or year or 3000-5000 miles seemed like a lot to me if I hardly use the car. Well, I've had synthetic oil in it for a long time. Just changed it last summer (myself), the old oil was pretty black. I figure to change it again this summer (have the oil already, Mobil 1 full synthetic, plus oil filter). Should I change that yearly?

I do keep my eye on the tires somewhat, check the inflation once in a while, have an AC inflator I picked up at Costco some years ago.

I'm guessing I should change the air filter, I have one but I heard it's not trivial on my car, I have to look into that. The car's close to 30,000 miles, so I'm thinking to have the 30,000 service soon, maybe at the dealership.

 

[tortillasoup]

That doesn't sound like much of a drive. Yes the synthetic and trickle charger is a good idea but like I've said, when you go for a drive, drive it MORE or don't drive it at all. The way you're driving it is a kind of in between which isn't good imo. Reason I don't like that climb is regardless of what ZV has said, the car does in fact run more rich when ascending a hill like that, dumping fuel into the oil. An engine that is cruising on the freeway on the other hand would just be light-moderately loaded while turning at a regular rate.


A lot of this is speculation though, I mean one thing you could do is to get an idea of how your driving habits are affecting your vehicle is to get a used oil analysis. Costs like $25 and should answer any questions about fuel contaminating the oil, premature engine wear, etc. etc. Considering it's a 1997 model car, it is likely to have problems in the future regardless so any issues you do see I wouldn't accuse you of causing them due to the way it has been driven.

 

[desy]

Your doing it right with the maint, on a lot of cars oil will go black quickly it doesn't mean its not doing the job, the only way to know is to get it analyzed
Just take a more scenic route on your longer runs

 

[Zenmervolt]

The car passed smog handily.Actually, in recent years during the winter, unless I'm making a Costco run (~6 miles each way, 1/2 on the highway), I may not do anything with the car except for a trip every week or two to the golf course to hit some range balls and putt. That trip is about 5 miles each way. However, it's up hill. The last mile or so is a climb of about 1000 feet, the whole 5 mile ride to the course is a rise in elevation of around 1100-1200 feet, a pretty steep climb (tough on a bicycle!) near the end. So, the engine and oil are (I figure) going to be pretty worked up in temperature by the time I get to the course.

That's not going to get the oil even close to full temperature. Frankly, that usage description is pretty much the worst sort of usage pattern for a car that you can get (short of taking it to redline with a full load 5 seconds after starting the engine in the middle of a winter in Fairbanks Alaska). The oil takes a LOT longer than the coolant to come up to temperature so just because the temp gauge on the dash says the engine's warm, that doesn't mean the oil's up to temp yet.

Here's an example. My motorcycle is air-cooled. Which means that it heats up the oil a lot faster and a lot more than a liquid-cooled car (because air-cooled engines actually use the oil to carry heat away from the heads). Even on 90 degree days it still takes the motorcycle 10-15 miles to get the oil up to 180 degrees. A liquid-cooled engine will take a fair bit longer to get the oil to temperature.

With the usage pattern you describe, you'll want to make sure you're following the "severe duty" maintenance schedule for your car. I would not go longer than a year on ANY oil. Even without much driving, there is condensation inside the sump and the water will react with the oil to form acids. Oil does contain additives to buffer those acids, but they don't last forever and without getting the oil fully to temperature to make the water evaporate out during your drives the time part of the oil change becomes even more critical.

You're doing well about the fuel tank though. Keeping it full reduces the amount of possible condensation in the tank and the increased volume of gasoline makes any dilution less of an issue.

ZV

 

[Lean L]

That's not going to get the oil even close to full temperature. Frankly, that usage description is pretty much the worst sort of usage pattern for a car that you can get (short of taking it to redline with a full load 5 seconds after starting the engine in the middle of a winter in Fairbanks Alaska). The oil takes a LOT longer than the coolant to come up to temperature so just because the temp gauge on the dash says the engine's warm, that doesn't mean the oil's up to temp yet.

Here's an example. My motorcycle is air-cooled. Which means that it heats up the oil a lot faster and a lot more than a liquid-cooled car (because air-cooled engines actually use the oil to carry heat away from the heads). Even on 90 degree days it still takes the motorcycle 10-15 miles to get the oil up to 180 degrees. A liquid-cooled engine will take a fair bit longer to get the oil to temperature.

With the usage pattern you describe, you'll want to make sure you're following the "severe duty" maintenance schedule for your car. I would not go longer than a year on ANY oil. Even without much driving, there is condensation inside the sump and the water will react with the oil to form acids. Oil does contain additives to buffer those acids, but they don't last forever and without getting the oil fully to temperature to make the water evaporate out during your drives the time part of the oil change becomes even more critical.

You're doing well about the fuel tank though. Keeping it full reduces the amount of possible condensation in the tank and the increased volume of gasoline makes any dilution less of an issue.

ZV

I probably don't know as much about the topic as you but why is it so bad? He's doing 5 miles. Assuming that he gives the car 1 minute to warm up, it should go through the motions pretty well. With modern engine oil I think it's enough protection to avoid any damage to the engine while moving everything around.

Although I agree 5 miles is probably on the cautious side of things. 10 miles should be good per single trip.

 

[Zenmervolt]

I probably don't know as much about the topic as you but why is it so bad? He's doing 5 miles. Assuming that he gives the car 1 minute to warm up, it should go through the motions pretty well. With modern engine oil I think it's enough protection to avoid any damage to the engine while moving everything around.

It's not about oil's ability to lubricate while the engine is running. It's about the oil getting hot enough, for long enough, for the water and other contaminants that get into it (from combustion blow-by, condensation inside the block, etc) to boil out and be vented through the PCV system. A 5-mile trip is simply not even close to long enough for that to happen. As I said before, the oil takes a LOT longer to come up to temperature than the coolant does. Just because the temperature gauge says the engine has warmed up does not mean the oil has.

Short trips are the worst sort of duty an engine can see. From the engine's perspective, he'd be better off letting the engine sit idling for the entire time he's at the driving range (obviously not recommended as a practical choice for many reasons) than performing a cold start, not driving long enough to build up heat in the oil, turning the car off, and then repeating the same process when heading home.

ZV

 

[Muse]

With the usage pattern you describe, you'll want to make sure you're following the "severe duty" maintenance schedule for your car. I would not go longer than a year on ANY oil. Even without much driving, there is condensation inside the sump and the water will react with the oil to form acids. Oil does contain additives to buffer those acids, but they don't last forever and without getting the oil fully to temperature to make the water evaporate out during your drives the time part of the oil change becomes even more critical.

ZV

Confession time! :$ I changed my oil (myself) one year ago come tomorrow. My notes say "Changed oil today at 25693 miles with All Synthetic Mobil 1." I think it may have been 10 years since the oil had been changed! :| I had a Blackstone kit to get the oil analyzed, but in the confusion I only got some of the last dribbling into the sample container. Blackstone recommends getting some of the main flush, not the dregs when sediment in accentuated. The sample container (still have it) is only ~1/4 full.

Well, obviously it being a year I should change the oil again. I'm going to do it tomorrow on the 1 year anniversary. I have everything I'll need including ramps that I bought for the purpose (last year I actually drove the front of the car up on big stones!).

Well, a couple of obvious questions:

1. How badly did I screw up the car not changing the oil for so long (I don't know if it was synthetic in there or not)? What can I expect going forward?

2. Should I send this sample to Blackstone anyway? Should I save a sample from what I drain tomorrow and send that to them instead? Should I send both samples??

 

[BUTCH1]

That doesn't sound like much of a drive. Yes the synthetic and trickle charger is a good idea but like I've said, when you go for a drive, drive it MORE or don't drive it at all. The way you're driving it is a kind of in between which isn't good imo. Reason I don't like that climb is regardless of what ZV has said, the car does in fact run more rich when ascending a hill like that, dumping fuel into the oil. An engine that is cruising on the freeway on the other hand would just be light-moderately loaded while turning at a regular rate.


A lot of this is speculation though, I mean one thing you could do is to get an idea of how your driving habits are affecting your vehicle is to get a used oil analysis. Costs like $25 and should answer any questions about fuel contaminating the oil, premature engine wear, etc. etc. Considering it's a 1997 model car, it is likely to have problems in the future regardless so any issues you do see I wouldn't accuse you of causing them due to the way it has been driven.

It's not so much "running rich" per se, if you climbing a hill and you need more power you depress the throttle and the EFI delivers longer duration pulses to the injectors, but that fuel is getting burned propelling the car up the hill, it's not "getting dumped into the oil", every car has a tiny amount of piston "blow-by" but these gases are collected and fed back into the intake manifold via the PCV valve. If your oil ever smells like raw gasoline you've got a problem, possibly extremely worn rings. In some older cars (before the electric fuel pump) the fuel pump was driven from the camshaft and bolted to the block. My last car with a mechanical fuel pump had a disaster, the internal diaphragm cracked, it still delivered enough fuel to keep the carb bowl full so the car was running fine, then one day at a stop light it starts billowing out enormous clouds of a light colored smoke, the entire intersection was a fog-bank!. I pulled over and check the oil, it was so overfull it was halfway up the stick, turns out the pump's leaking diaphragm was pushing raw fuel into the crank case, it thinned the oil so much the rings gave out on at least 2 cylinders, I had to scrap it..