service intervals

This topic contains 7 replies and was last updated by dan-bates 9 years 9 months ago
Author
dan-bates
December 26th, 2011 2:29am
Post
i am curious what the general oil change and service intervals are for 8 axle crude oil hauling tractor trailers in north dakota oil fields. right now they change at 250 hrs that seems awful soon. what do you gentalmen and ladies feel is the right interval?
ben
December 26th, 2011 3:25pm
I drop oil at 250 hr intervals whenever I can. 250 hrs at 100 kph works out to be a oil change for every 25000km on the road, if your steady haulin with any kind of weight that oil is wearin out. I don't work on haul trucks very often but it seems like a good preventative measure.
jim-owen
December 27th, 2011 7:22pm
250 hrs. for oil changes can be too short and waste serviceable oil, or it can be waaay too long in other conditions. The only way to know for sure is via the oil sampling route. Oil sampling tells you a lot of things more than just the cleanliness of the oil, so to sample just for cleanliness, is way too costly.



However, using the 250 hr standard to change oil is reasonable. By comparison, oil changes are the cheapest form of preventative maintenance. In some situations where the truck or piece of equipment is run continuously with few or no cold starts, in a clean environment, with a properly sealed and vented engine, the oil could last substantially longer. This does not happen very often.



More likely an engine will have some minor air leaks allowing some dust into the oil. The crankcase ventilation system puts the engine crankcase under vacuum conditions and unfiltered air gets in somewhere. The turbo always creates some sooting of the oil, the more worn the turbo, the more soot it creates. The EGR systems are another place soot can be generated. And let's not forget the normal engine blowby with the soot and other particulates generated by combustion. Add in normal wear of the engine, and that oil filter has a lot of work to do.



It is possible that some systems have differential gauges for the engine oil filters to tell you when the filters are plugged but on engines they are very rare. The oil filters go into by-pass at a 4 to 5 lb. differential.



And you don't know when.
jim-owen
December 27th, 2011 8:11pm
I just thought of a scenario where an OBSERVANT operator might notice that the filter may have gone into by-pass.



The oil pump creates the flow and the restrictions in the engine creates the pressure. If the oil pressure sender is after the full flow oil filter, the operator would not be able to tell. However, as in most situations, the oil pressure sender is ahead of the full flow oil filter, the OBSERVANT OPERATOR might notice that the pressure suddenly became less.



The full flow oil filter is a restriction in SERIES with the bearings and whatnot in the engine. When you have restrictions in series, it creates a higher back pressure. When the full flow oil filter suddenly goes into bypass, the back pressure is lost, the operator might notice that the oil pressure suddenly dropped that 4 to 5 lbs. and the sender is able to pick that up.
john-whelan-2
January 22nd, 2012 6:59am
Hi Dan, I agree with the 250 hr interval especially with construction equipment and severe duty conditions. The idling time doesn't count with mileage intervals so there is never any accuracy to that PM feature. Jimo has covered this subject very well already :)
joshua-melber
January 23rd, 2012 11:37am
Yep, i definitly agree with 250, that oil has got to be beat pretty good working hard out there in the dust.
jim-owen
January 23rd, 2012 5:33pm
It should be understood, as well, that 250 hrs. should be considered a mean average. There are pieces of equipment that, because of what they do, should be considered to be serviced more frequently than 250 hrs. Ones that come to mind now are: street sweepers, combines and others that work in severe dust environments. Again, probably the only way to know for sure is by sampling.
doug-niemi
February 9th, 2012 9:03pm
Generally 1 hour of idle/run time is the equivalant to 25 miles driven. I find this a good R.O.T. (rule of thumb). So 250 hours would be the equivilant of 6,250 miles. Service intervals can be adjust up or down based on the operating conditions for which it is used. It sounds like you are describing fairly dirty and dusty operating conditions (probably better to error on the side of caution until you know differently). The other option would be to look into oil analysis (sampling) to determine if 250 hours is too soon or too late and adjust service intervals based test results.

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