Idling vs shutting off - effect on engine wear?

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Accent Abuser

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As many of you know, I do rideshare for a living, and therefore drive 200+ miles a day. Lately it's been kinda slow so there are times when I'm just sitting in the car waiting for a fare and that got me wondering, from a purely engine longevity standpoint, which is worse, shutting the engine off and restarting it 20+ times a day or just letting it idle?

Obviously I know idling is worse for gas mileage, I'm just curious which causes more wear, especially in the freezing cold Northeast winter, where 20 minutes is enough time to cool the engine to less than 100°f.
 
Both are bad, but I think shutting off and restarting is probably worse.

I would do something productive with the time, such as add another delivery/transport service like door dash, Uber, Lyft, etc. Many folks triple dip, so to speak, on a lot of services so they are not idle.
 
Highly dependent on the engine. The V8's in our Chargers are almost all developing some ticking. Don't think we've had any failures, but we're right in the middle of ditching the Chargers for Ford SUV Police Interceptors (Explorer). Granted, its a different division from mine, so I only see/hear the cars when they stop by the jail. I do know they didn't tick when new, and they idle a LOT in a 12 hour shift. It's my understanding that the Dodge motors suffer from below par oil pressure at idle that eventually causes camshaft/lifter damage.
 
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Creekside said:
I would say shutting off and restarting. We were taught in diesel school that 80% of normal engine wear occurs at startup when the oil is trying to come up to pressure.
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Not with a warm engine. And the biggest thing is that startup wear is overrated these days because the antiwear additives form a sacrificial barrier even when nearly all the liquid oil is drained to the bottom. And if only shutting down for 10-15 minutes at a time there will still be a decent layer of oil everywhere. Anyone who looks inside a valve cover with an oil filler cap can see that. I had a look at it after 8 hours since it was last driven, and there's still a decent layer of oil everywhere.

However, a lot of newer cars have stop-start mechanisms where there's no control over it unless I guess the driver gooses the engine periodically.
 
atikovi said:
Stress and wear on the rings and bearings has to be pretty minimal while idling, but if you're stopped more than 2 minutes, it's saves more gas if you shut it off. Starting a warm engine shouldn't cause measurable wear.
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Not 2 minutes, it only takes about 10 seconds.
 
LeakySeals said:
Newer vehicles are shutting off at every stoplight. In gear. No big deal for the engine but I wonder about starter and transmission wear long term.
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Heavy duty starters designed for this purpose, and I believe the transmissions have a separate oil pump (in automatics) to keep line/solenoid pressure up while the engine is off. I know the Aisin 8 speeds (both FWD and RWD) use that method.
 
At 200+ miles per day of driving I don't think it will matter much either way. Racking up miles that quickly, it's more likely that something else like an accident, transmission failure, or other expensive component failures will take the car off the road before the engine itself wears out.
 
fisher83 said:
At 200+ miles per day of driving I don't think it will matter much either way. Racking up miles that quickly, it's more likely that something else like an accident, transmission failure, or other expensive component failures will take the car off the road before the engine itself wears out.
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Not if I can help it, I take good care of it and replace parts at the first sign of failure, do all fluid maintenance early, keep the salt off and undercoat in the winter. I've replaced most of the suspension parts because the roads here suck. The 6spd auto is pretty bullet proof, but I like this car enough that I'd replace it if it ever did go out.
 
Accent Abuser said:
Not if I can help it, I take good care of it and replace parts at the first sign of failure, do all fluid maintenance early, keep the salt off and undercoat in the winter. I've replaced most of the suspension parts because the roads here suck. The 6spd auto is pretty bullet proof, but I like this car enough that I'd replace it if it ever did go out.
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I think it's safe to say that all of us are on here because we care about properly maintaining our cars. But 200 miles per day works out to over 50,000 miles per year assuming a 5 day work week. 6 years at that rate would put you at 300,000 miles. That's a rarely reached milestone even here in BITOG world.
 
fisher83 said:
At 200+ miles per day of driving I don't think it will matter much either way. Racking up miles that quickly, it's more likely that something else like an accident, transmission failure, or other expensive component failures will take the car off the road before the engine itself wears out.
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200 miles a day is likely to be fairly easy on the engine since it will never get cold and warm starts are actually pretty easy on the starter. I remember a Pennzoil commercial claiming that a business using a pickup as an escort vehicle for oversized loads had its oil changed every 3000 miles, but that's probably not needed for that little mileage when it racks up that many miles with relatively few starts.

The brakes and suspension are going to be pretty messed up though.

Still - for this kind of driving an EV might actually be ideal since there really isn't much of a concept of needing to warm up anything. And idle breaks can be taken at charging stations.
 
Accent Abuser said:
Not if I can help it, I take good care of it and replace parts at the first sign of failure, do all fluid maintenance early, keep the salt off and undercoat in the winter. I've replaced most of the suspension parts because the roads here suck. The 6spd auto is pretty bullet proof, but I like this car enough that I'd replace it if it ever did go out.
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I think it's safe to say that all of us are on here because we care about properly maintaining our cars. But 200 miles per day works out to over 50,000 miles per year assuming a 5 day work week. 6 years at that rate would put you at 300,000 miles. That's a rarely reached milestone even here in BITOG world. A
y_p_w said:
200 miles a day is likely to be fairly easy on the engine since it will never get cold and warm starts are actually pretty easy on the starter. I remember a Pennzoil commercial claiming that a business using a pickup as an escort vehicle for oversized loads had its oil changed every 3000 miles, but that's probably not needed for that little mileage when it racks up that many miles with relatively few starts.

The brakes and suspension are going to be pretty messed up though.

Still - for this kind of driving an EV might actually be ideal since there really isn't much of a concept of needing to warm up anything. And idle breaks can be taken at
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y_p_w said:
200 miles a day is likely to be fairly easy on the engine since it will never get cold and warm starts are actually pretty easy on the starter. I remember a Pennzoil commercial claiming that a business using a pickup as an escort vehicle for oversized loads had its oil changed every 3000 miles, but that's probably not needed for that little mileage when it racks up that many miles with relatively few starts.

The brakes and suspension are going to be pretty messed up though.

Still - for this kind of driving an EV might actually be ideal since there really isn't much of a concept of needing to warm up anything. And idle breaks can be taken at charging stations.
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Another factor is how economically feasible it will be to keep on the road. Subcompact cars tend to depreciate pretty quickly under normal circumstances but that would be accelerated to a degree by the high mileage. Soon you're faced with repairs that easily exceed the value of the car and you have to decide whether it is worth spending the money. One such example was my grandmother who bought a brand new Geo Metro in the mid 90's. It was a fairly reliable car for the first 100k or so but she spent more in the next 30-40k miles than the car was worth just fixing wear and tear items and repairing the AC. At the end of the roughly 10 years she had it she got $500 for it on trade-in. I'd just do whatever is more comfortable for you as a driver whether that be idling or shutting off and re-starting. Spending that much time in the car, I'd value comfort over any perceived gains in longevity.
 
i have no scientific study to back up my behavior, but if I am stopping for more than 1 minute, I shut off the car. I believe idling causes Carbon deposit issues. It also consumes gas needlessly.

As others have stated I think up to ten minutes or so, the engine oil is still so warm that start up wear will be negligible. Maybe 5 minutes tops if in a northern winter. I am not comfortable with idling and carbon deposits.
 
fisher83 said:
Another factor is how economically feasible it will be to keep on the road. Subcompact cars tend to depreciate pretty quickly under normal circumstances but that would be accelerated to a degree by the high mileage. Soon you're faced with repairs that easily exceed the value of the car and you have to decide whether it is worth spending the money. One such example was my grandmother who bought a brand new Geo Metro in the mid 90's. It was a fairly reliable car for the first 100k or so but she spent more in the next 30-40k miles than the car was worth just fixing wear and tear items and repairing the AC. At the end of the roughly 10 years she had it she got $500 for it on trade-in. I'd just do whatever is more comfortable for you as a driver whether that be idling or shutting off and re-starting. Spending that much time in the car, I'd value comfort over any perceived gains in longevity.
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So many gas powered cars have automatic stop-start, so there may not be an option. It'll just shut off and I suppose also shut off the heating and/or A/C.

Still - I'm kind of wondering what happened to a supposed future I read in electronic industry publications in the 90s. They were talking about 40+ volt power systems in cars that could power more sophisticated electronics and electromechanical systems better and more efficiently than 12V systems. That might have made electric A/C more practical where it could be operated when the engine is off. This is an article from a few years ago, but I remember this in the 90s but it never really went into production.


Or older talk about this.



 
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