Seemingly Stupid But Valid Question--Why Odometers Rather Than Hour Meters?

savatage1973

Addicted Member
I was just going through and servicing some of my heavy equipment, preparing for winter. All of this equipment uses hour meters to measure actual run-time which dictates the service/maintenance schedule.

It would seem that this would also be the "better" method for determining service/maintenance schedules for automobiles--especially for hybrids where the engine does not run all the time that the vehicle is racking up miles, or vehicles that sit idling for long periods of time--3000 miles at <35 mph is a lot more run-time and wear and tear, than 3000 miles at ~65 mph.

I realize that most vehicles have (or used to have) "heavy service" maintenance schedules with more frequent service intervals, but why not just use an hour meter like on heavy equipment? It would seem to make more sense.

A cop car or taxi that sits idling 12 or more hours a day (racking up very few miles) may certainly hit a service interval (dictated by hours of operation) long before a mileage point is reached.

Just a dumb question that struck me as I was logging the hours on my equipment as I was performing service on it.
 
It makes some sense to measure engine time rather than distance covered but it also makes even more sense to measure time the engine runs at low, mid and high engine revs.

Compare the following:
A 100 km (160m) distance covered in 1 hour
The same distance covered in 45 minutes.
The same distance covered in 2 hours.

What would wear the engine more?
Cruising at an average speed of 50km/h is certainly boring but it wouldn't strain the engine. At winter time it would even run cool and happy.
Driving at 100km/h would certainly wear the engine more but perhaps not much more. It might even give the least fuel consumption.
Doing the same at an average 130km/h would be harder for the engine. I know it does put some more strain in mine that burns some oil during normal driving but burnt half a liter during a 400km trip that was done at that average speed.
 
cuz the question is actually in reverse order: why hour meters instead of odometers.

gensets, tractors and harvestors dont cover many miles. and (generally) have fixed operating ranges

in a vehicle, 'how far did you go' makes more sense than 'how long was it running'
 
Police cars and such sometimes have hour meters for maintenance reasons for exactly the reasons gensets do. Newer vehicles often have an hour counter in the information display someplace if you cycle through. A fancypants scanner can pull it if not.

As for the wear thing based on driving, thats where the oil life monitor comes into play. The computer will tell you when the oil needs to be done based on time, mileage, and driving conditions rather than just run time or miles driven.
 
It makes some sense to measure engine time rather than distance covered but it also makes even more sense to measure time the engine runs at low, mid and high engine revs.

Compare the following:
A 100 km (160m) distance covered in 1 hour
The same distance covered in 45 minutes.
The same distance covered in 2 hours.

What would wear the engine more?
Cruising at an average speed of 50km/h is certainly boring but it wouldn't strain the engine. At winter time it would even run cool and happy.
Driving at 100km/h would certainly wear the engine more but perhaps not much more. It might even give the least fuel consumption.
Doing the same at an average 130km/h would be harder for the engine. I know it does put some more strain in mine that burns some oil during normal driving but burnt half a liter during a 400km trip that was done at that average speed.
Your premise assumes you're on flat roads. Driving up to 10,000' the vehicle is going slower and working much harder than when it's gravity assisted and flying downhill.
 
probably the ratio of idle to drive time in cars makes more sense to calibrate maintenance
to miles, tractors and such are better off with time meters if for no other reason than
the history of its use dictates the maintenance periods. each has it's primary usage
measured against historical data.

then there's Crown Vics with an idle meter that fires off the boys when the ex-cop P41s
show large amounts of time idling. similar to the decades old Consumer reports about
NYC taxis showing no wear running 24x7 and none of us believing any of it.
 
in a vehicle, 'how far did you go' makes more sense than 'how long was it running'

I don't necessarily agree. Running is running--whether it be moving or not. As hours rack up, lubricants and coolant still deteriorate, everything is still under heat stress, bearings and belts still wear. I know cops that will put on maybe 50-100 miles in a shift, but the car has sat on the side of the road on a 90+ degree day with the A/C running for at least 8-10 hours--that is a lot of "wear and tear" for virtually no miles on the odometer.

In all reality, I'd rather buy a 2 year-old used car with >100K miles on it, than a 20 year-old used car with <50K on it. It has either just "sat" unused and deteriorating, or only driven a few miles a week for its entire lifespan--again not good.
 
Too hard to re-train the general public.

Well, with the bulk of new cars having "service reminder" warning lights on the dash telling you when to head back to the dealer for scheduled maintenance, an hour meter tied into the computer system would work just fine. Most idiots with new cars only know how to start it and where to put in gas. Hell, my one employee's wife probably doesn't even know where to put in gas because he fills her car up once a week for her.
 
I bet that the hours versus miles ratio has something to do with maintenance versus warranty concerns.
 
Hours are fine for engine maint. Not so good for brakes/lubrication. Engine hours might lead to premature replacement of brakes/bearings struts and suspension components.

Mileage is a decent cross-purposes indicator for general service.
 
for oil changes i think it would be best to monitor the contaminants in the oil .after all the oil doesn't wear out it just gets dirty . or so i was lead to believe.
i have looked for shiny metal flakes in engine oil plenty of times to see what is likely worn before buying a vehicle . am sure today's technology could have sensors for this early warning system .
 
Boats and industrial equipment are mostly on or off. They are considered under load while running. Cars live a very different life, the load varies depending on conditions. Load is what puts stress on engines. That's why you see engines with ridiculously high mileage, they are running 1800 RPM on flat ground for hours at a time. Load often determines service intervals.
 
Hours are fine for engine maint. Not so good for brakes/lubrication. Engine hours might lead to premature replacement of brakes/bearings struts and suspension components.

It can work either way. If I drive only a few miles in all stop and go traffic "light-to-light" every day, I could kill lubricants and brake pads far more rapidly than doing 100+ miles a day on the highway. Suspension components are a different story, basically determined by age and road conditions.

for oil changes i think it would be best to monitor the contaminants in the oil .after all the oil doesn't wear out it just gets dirty . or so i was lead to believe.

There are places that will test oil for contaminants, but the cost is usually the equivalent of an oil change. I agree that most modern synthetic or synthetic blend oils don't degrade like old-school conventional oils. Something I learned from an old fleet/taxi mechanic was to change the oil filter frequently and just top off the oil level--and do the full oil and filter change at every other interval. The oil is good for the 8-10K miles, but the filter needs to be changed at half that interval. I have used this method on a number of vehicles over the years with no issues, so I guess he was right.
 
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