Run time in hours versus miles

[rhunt]

This may be of interest to those of us who have Continental engines on equipment we use. This could also be used on any engine as long as it is running at 1800 RPM and has a hour meter.
This info is from a manual for my Onan genset built back in '59 which is powered by a Continental 162.
"To arrive at an approximate figure of comparative generating plant running hours as against automobile engine running miles, multiply the total number of running hours by 41 to find the equivalent of running miles on an automobile".
Examples for clarity:
1 hr = 41 mi
8 hr = 328 mi
240 hr = 9840 mi
Hope this info helps you on the scheduled maintenence of your engines and also just how many miles that girl has on her!! Bob

[drujinin]

Maybe 41 mph in 1959 but in 2011 maybe 51 mph?

[Brink, M.E.]

Being a geek at heart, I had to pull out my maintenance log and crunch some numbers to see how the guide and real world numbers matched up. First a little background . . . I perform all maintenance on my truck, keep receipts, and record EVERYTHING. When I change my oil I record both mileage and engine hours. The majority of my driving is to and from work (76 mile round trip, mostly 55-70mph roads)

With that in mind, the numbers from my last two oil changes were 7031mi/161.5hrs/43.5mph avg. and 7690mi/174hrs/44.2mph avg.

So sparing all the gory details (vehicle, engine, temps, oil, driving habits, gear rations, tire size, idle vs driving time, etc.) it looks like the 41mi rule of thumb will get you pretty close (in my case anyway) I won't even get into how I started to really geek out and figure out what kind of gear ratio/tire size combo the whole 41mi/1800rpm related to.

[denrep]

Interesting calculations.
I use a slightly different formula, one that with a glance I can calculate in my head.

I multiply hours by 100, because it's easy, and worst case I presume "they've" been running the engine just like 100 MPH.

Then I multiply the result by some factor like ½, 1/3, 1/4, or maybe 1, depending how severe the engine's service seems and how durable the engine model typically is.

Examples:
1000 hours, with a boat that's pulling hard all the time:
1000 x 100 x 1 = 100,000 miles equivalent

1000 hours with a compressor or welder that unloads and idles a lot:
1000 x 100 = 100,000
100,000 x.25 = 25,000 miles equivalent

Good Luck

[Stick-man]

I used to change the oil in my semi trucks by milage. Now I do it by hours, which I was told was more accurate, in case you were working on site alot. But I remember the local Caterpillar dealer telling me that fuel consumption was the most accurate. That takes into consideration how hard the motor has worked.

[ASE_MasterTech]

'Hour meters' are far more accurate than 'Mileage' for determining wearable issues or intervals for service (as 'mileage' does not include idling times, among other things)
'Hour meters' are now present in all current motor vehicle engine control modules...

[denrep]

. . .I remember the local Caterpillar dealer telling me that fuel consumption was the most accurate. That takes into consideration how hard the motor has worked.

That makes a lot of sense to service by fuel consumed.

Used to be that Caterpillar "hour meters" were actually service meters which counted engine revolutions. I'm not sure of the exact ratio but I believe that one hour at rated speed would clock one service unit.

[NVW]

My system is easy, oil and filter every 100 hrs if it has an hour meter. Whether it's my welder, tractors or combine.

[Brink, M.E.]

I change my oil when the dummy light tells me to

[rhunt]

Leo, your method corresponds to Onan's maintenance schedule. Good rule of thumb!! Bob

[76GMC1500]

100 hours = 3000 miles.

[duaneb55]

I change my oil when the dummy light tells me to

Doesn't the 'puter take into account all factors? Driving conditions/habits, idle time, temps, etc?

I know your brother's Beamer did. He could go from a 10K service interval to 8K based on the position of his right foot.

[daddy]

I think you are correct duane, at least with gm products that I have driven. The mileage is not the same when it tells you to change the oil...I don't know what all is factored in though.

[duaneb55]

Brink, M.E. just told me the manual states engine RPM and coolant temp are the two factors the computer takes into account.

[MX727]

My Ford has an hour meter. Turns out that that estimate is pretty accurate. Last time I checked, I was averaging 42 mph. And that is with a lot of HWY miles.

[drujinin]

I brought up the subject on a couple of construction equipment websites. 41mph seems to be pretty accurate as one guy is on Long Island and regularly commutes into New York City. A guy in Canada sort of out on the praire said that his too comes out close to 41. So I am going to stick to the 41mph rule of thumb and call it good!

[Stick-man]

Looked at my Mack and it has 196617.2 miles and 10089.2 hours which equals 19.48 miles per hour average. Using that and changing my oil at 400 hours would equal 7792. And that is right about where I like to be. 7500 - 8500 miles, since it is a newer truck. And well below the recommended. And on my F-350, I use regular dino oil, 15W-40 and change it at 3K miles. Oil is cheap!

[paintman40]

And on my F-350, I use regular dino oil, 15W-40 and change it at 3K miles. Oil is cheap!

And your wasting it.

Get some oil samples, You'll be surprised how much further your oil change intervals can go. When we was running a Cat engine fleet west coast, we changed at 35,000 miles and oil samples still came back with room to spare. Now, our Cat fleet is all local (~150mi radius) and I change in the 10,000 mi. range. BUT that only equals to about twice a year. After about 6 months, I worry about moisture content.

[76GMC1500]

What tests were being done on your samples. The standard test will come back with ppm of various metals in the oil. Zinc, phosphorous, etc... are additives put into oil for anti-wear. Most oil analyses test for these metals and any depletion would indicate time for a change. But, these metals are usually part of chemical compound and simply their presence doesn't mean they are still effective. There are other tests that need to be done such as an infra red fourier analysis. Also, with diesel engines the oil has a soot dispersant which can only suspend so much soot. If you push the change interval too far you'll start getting soot deposits regardless of the condition of the anti-wear pacakage.

That being said, our fleet runs Delo 400 in the 4-strokes and Delo 477 in the 2-strokes. We always get complimented on the condition of our camshafts and have never had significant wear at an overhaul. We do changes at 500 hours (15000 miles by the 100 hours=3000 miles rule) on our John Deere 8.1L engines. 14,000 hours a piece between 8 with only one injector failure and many alternator failures. Rest of the fleet runs cat 3512 engines. We've run 8x10,000 hours and 2x35,000 hours with no failures. They get oil changes at 1500 hours or 45,000 miles. The 2-strokes never get oil changes, we've got 40,000 hours on two engine and 80,000 hours or two more... two failures. One may have been an improperly tightened connecting rod bearing cage and the other is unknown we just know the block has a serial number 10 years newer than the boat.