Highway miles better for life of motor?

[Ed_Flecko]

I used to think that carburetor equipped car motors would run run longer and smoother if the bulk of their miles were highway driven at the speed limit. I think that's probably still true, to a certain extent, but I'm not sure it makes much difference with fuel injected, newer vehicles?

I drive about 20 miles to work/home every day, round trip. It takes me about 20-25 minutes to get to work, and my temperature gauge shows that my motor has easily been running at normal temperature. My motor averages at about 2200 RPMs as I make my way down the boulevards, surface streets, etc. When I was actually driving today on the freeway, I noticed my motor runs at about the same RPMs at freeway speeds, which got me wondering...

Does it make any difference to my motor life that I'm driving on surface streets -vs- freeway given that my RPM range is pretty much the same? How about the rest of the vehicle?

Ed

 

[Olas]

There's more stopping and starting around town, along with more potholes, so you could say highway miles are better for clutch, brakes and suspension.

As far as the engine is concerned, I might be wrong but I think it's more about time spent at operating temperature rather than which kind of roads you do the miles on. That said, it's easier to spend time at temperature on the motorway than it is in the city..

With proper maintenance I don't think either will harm the engine, they were designed to be tough.

 

[eljefino]

I think the biggest thing would be the idea that a highway trip is a long trip and the thermal expansion would "settle in" and the one cold start would be spread out over hundreds of miles.

You could find a city driven taxi with a bazillion miles, good motor, and shot tranny and front end.

 

[WobblyElvis]

ON the freeway you are usually going faster and the transmission is in a higher gear. You cover more ground with same amount of engine revolutions. Less wear per mile on the freeway. Provided the surface streets are driven at a lower speed.

 

[OneEyeJack]

Steady state driving over a longer period is better, within reason of course. By that I mean driving at a reasonable speed without being overweight.

Stop and go driving takes more fuel and causes more wear. Some fleet operators that use utility vehicles off road and in difficult conditions change oil based on the amount of fuel consumed.

 

[bubbatime]

Originally Posted By: Ed_Flecko
I drive about 20 miles to work/home every day, round trip. It takes me about 20-25 minutes to get to work, and my temperature gauge shows that my motor has easily been running at normal temperature.


There is coolant temp and oil temp. The temp gauge only monitors coolant temp and not oil temp. While it may say that the engine coolant temp is normal after 5 minutes, it actually takes about 25-30 minutes or longer for the oil temp to get to its operating temperature.

 

[barkingspider]

yup, I notice the revs are lower cruising on the FWY vs stop and go in town.

 

[4wheeldog]

Way back when the earth had not yet cooled, and I was a child, my father worked for a major petroleum company.

He was an accountant and told this tale in way of explaining a principle of constant vs. intermittent use.

It seems the company he worked for had two main offices about 90 miles apart. They kept a couple of messengers on duty 24/7, and used 2 cars to constantly shuttle reports/mail/whathaveyou back and forth. The cars were not shut off, except for fueling, for a week at a time. They used these cars for 500k miles, with maintenance schedules tripled, from manufacturer's requirements. This back in the late '50s, when oil was basically liquified dinosaur......And most cars were on their last legs at 100k miles.

My uncle worked for the same company, but as a plant mechanic. His explanation holds true today......Most wear occurs in startup and warm up. If you run a vehicle constantly, there is minimal wear. Shut it down, and the wear occurs until it is up to normal operating, again.

 

[HTSS_TR]

Highway miles are easy on these parts too: brake and manual transmission clutch. These two are rarely used on highway miles, but constantly in stop and go city traffic.

 

[friendly_jacek]

last time i gave it some serious thoughts i concluded 1 city mile = 2-3 hwy miles. the suburb miles are harder to calculate, but safe to assume 1 suburb mile = 2 hwy miles.

 

[hpb]

Originally Posted By: Olas

As far as the engine is concerned, it's more about time spent at operating temperature rather than which kind of roads you do the miles on.


Olas hit the nail on the head. The engine doesn't care where it is, as long it's up to operating temperature.

 

[TiredTrucker]

And now folks understand how many commercial over the road semi truck engines go well past 1 million miles before the engine is ever opened up for anything. I took a FLD120 with a Cummins N14 to 1.4 million miles, sold it, and it went right to work for next owner. All that motor got during it's lifetime was 1 injector and a accessory drive seal. It got 30K mile OCI's on Kendall conventional.

 

[Clevy]

Most wear occurs during the warm up phase when the oils heat activated additives haven't turned on yet so the less frequently the engine is in this phased the less wear occurs.
High load and low rpm will wear faster too. When I a high load scenario it's better to have a few more rpm.
Highway miles tend to be lowish load and low rpm so there will be less wear per mile vs city miles.
Jack rabbit starts are hard on bearings too.

 

[HangFire]

Originally Posted By: Ed_Flecko
I used to think that carburetor equipped car motors would run run longer and smoother if the bulk of their miles were highway driven at the speed limit. I think that's probably still true, to a certain extent, but I'm not sure it makes much difference with fuel injected, newer vehicles?


There's no doubt a properly calibrated fuel injected motor will outlast a carburetor motor, which suffers momentary hot lean conditions that are hard on exhaust valves, and momentary rich conditions that produce a lot of carbon fouling.

Those boundary conditions occur more often in stop/start city driving than highway driving.

 

[Doog]

My wife's car is used about 70% highway miles and at 200k using synthetic oil and 5000 OCIs they consistently run like new and do not consume more than 1/3 to 1/2 quart of oil in 5000 miles. The last 2 trades at 200k had original suspension and brake rotor/calipers. Brake pads last 70,000-80,000 miles.

My car (same engine as hers) on the other hand is a short tripper (2 miles commute)doesn't fare as well. By 200,000 miles it is ready for trade all the way around. Brake pads last 55-60,000 miles. struts need replacing at 120-140,000. Rotors are gone by 140,000.

 

[Kestas]

I've seen data on wear tests that studied this. Highway miles are much easier on the motor than city miles. No great surprise.

 

[Cujet]

As mentioned above, the engine accumulates fewer hours per mile on the highway.

For as long as I can remember, travelling salesmen were always able to achieve far more miles on a vehicle than the normal owner of the very same car.

 

[CBR.worm]

Right, significant difference. In my own experience, 40k a year on the highway requires fewer replacement parts than 10k a year around town.

It was a real eye opener to see the difference, and realize that miles alone are not a very good metric for judging the life expectancy of a vehicle. It would be much more useful to have an hour meter as well.