Hour meter instead of milage for service intervals

[CrazyMike]

Like I've mentioned before, I have a '04 Jeep with a stroked I-6, I'm a bit excessive on servicing but mainly for the fact it sees 98% off road. Dirt, mud, gravel, water, etc, the only pavement is to and from the house. With the engine intervals it's been a bit of guesswork. I may drive for 8 hours straight but I may not even put on 30km's the whole day, it's spent crawling through trails, chewing through mud, or idling while I clear sections of trail from debris. I don't shut it off when I'm out touring, I'm always solo and I don't have a spare starter with me. I'm sure the bears or moose won't offer to help push start, heheh.

In the day of extended intervals I'm ashamed to say I probly, on average, am closer to a 2,000km interval than 5,000km as stated in another thread. Hour-wise, I don't think I'm that far off to a 5,000km interval.

What do you guys think, my mechs do all the commerical vehicle maintenance on site by the hour, if I'm not adding up the km's why can't I do the same?

Also, would using synthetic over mineral still benefit, currently using up my Supreme 10w40 stock, Delo 400 5w40 synthetic is plentiful.

Thanks in advance!

 

[MGregoir]

If you have an hour meter, I would change it based on say 5000 km divided by 50 km/h is 100 hours.

You are going to be sucking a lot of dirt and stuff so the shorter interval makes sense, if it was pavement, on road miles, I would suggest at least 160 hours before changes.

 

[JHZR2]

driving 3000 miles at 55 mph is different than driving 3000 miles at 5 mph. Similarly, driving 1000 hours at 55 mph is different than driving 1000 hours at 5mph.

In a lot of ways, one is an analog of the other, so long as the use profile is consistent, which it is for you. I dont see an hour meter as necessary.

I would leverage off of city police and taxi fleet data as a first run indication of interval, as theirs is much the same - long time turned on, few restarts, but not necessarily a lot of movement.

Id probably tune off of a miles-based UOA analysis from there.

It is an excellent question.

JMH

 

[MGregoir]

I would like to know the average speed for oil change intervals, I would imagine that a 7500 mile oil change interval would be based on 7500 miles at 60 miles per hour, or 150 hours, and 3000 miles would likely be based on 20 miles per hour for "severe service" using my car as an example for run time versus mileage.

Fuel consumption would be another way to do this. 7500 miles at 30 miles per gallon is 250 US gallons of fuel, or about 950 litres. Mileage tanks due to low speed and idling, then OCI goes down accordingly.

I just got a UOA back from 3000 miles on Mobil 1 5W-30 in very severe service, mostly city driving and no block heater in an Edmonton winter, and it said I was still good for at least another 1,600 km in those conditions, and in summer I could likely go much longer.

I saw the formula here before, but I think it would be neat to develop a baseline delta for SM/GF-4 oils hours versus miles versus fuel consumed to calculate oil change intervals. With OBDII electronics, fuel consumed would add the factor of open or closed loop operation and cold starts as well to give a nice triangular box to work with.