Oil Change By Hours?

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Jul 11, 2021
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Ok so I have a 2020 F350 with 7.3L Gas motor that idles a lot, I started a thread awhile ago on a different forum asking what might be a good OCI going by hours. Link to first thread. It has more info about my specify application.

I did a 200hr oil change and sent the sample in to my local cat dealer for a UOA, also sending one to blackstone for fun.

Here is the UOA from Cat: UOA

Looks like still lots of life left, I don't see fuel dilution anywhere however, would like that info.

Thinking I will go to 250hrs this time? Thoughts?

PS: Here is a link to a VOA on the same oil: HERE
 

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b_b

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oil life monitor take into account the idle time. i change mine around 30% or so. usually comes out to about 5k depending on weather. extreme cold the olm falls like a rock.
 

JWC86

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oil life monitor take into account the idle time. i change mine around 30% or so. usually comes out to about 5k depending on weather. extreme cold the olm falls like a rock.
This gets thrown around a lot but I'm not sure its a great indicator, My most recent OCI was 2,883 miles / 204 hrs, 139 of hours those being idle time.

If we use fords recommendation of 33 miles per hour of idle time that would be another 4587 miles for a total of 7,470 miles. My OLM was at 51%, so that would be a 15k mile OCI if ran to 0%

To make things worse, that OCI had more driving than typical for me, I suspect my normal OCI with less miles and more idle hours would be even worse.

I think for now I will stick with 200-250 hrs.
 
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250 hrs is a good place to start, but I would be surprised if the OLM was not allowing for the conditions you are concerned about. I would run the next change until the OLM tells you to change the oil, and perform a UOA at the time.
 

pcf

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Fords testing with police cars settled on idling = 33 miles an hour.
I have no idea how Ford could have gotten that number. In the days before smart phones when patrol cops would drive in circles to pass the time 10-12 miles per engine hour would have been a lot of driving. Now days most of the cars I manage are in the single digits. This is a pretty typical car, when it's in motion it's 23 miles per engine hour. Almost 8 miles per hour in total. How is sitting at idle compute to 50% more per miles per engine hour, than when the vehicle is in motion? I don't see how that's possible. Obviously this is a Dodge and not a Ford.
 

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JWC86

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250 hrs is a good place to start, but I would be surprised if the OLM was not allowing for the conditions you are concerned about. I would run the next change until the OLM tells you to change the oil, and perform a UOA at the time.
Great reply and makes the most sense. I don't think I could let it go 500 hours however. Maybe working up to it 50hrs more at a time however.
 
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I have no idea how Ford could have gotten that number. In the days before smart phones when patrol cops would drive in circles to pass the time 10-12 miles per engine hour would have been a lot of driving. Now days most of the cars I manage are in the single digits. This is a pretty typical car, when it's in motion it's 23 miles per engine hour. Almost 8 miles per hour in total. How is sitting at idle compute to 50% more per miles per engine hour, than when the vehicle is in motion? I don't see how that's possible. Obviously this is a Dodge and not a Ford.

That number originally came from a fleet report years ago prior to DI.

I'd imagine they carefully measured a number of parameters over time, but I cant quite say for certain.

I also imagine that a cop car likely has a higher output alternator to run all the electronics, lights, etcetera, so that contributed a bit to the load.

Being "in motion" is pretty arbitrary. Maybe 1 hour its 10-12 , or even 8 miles but in the second hour its a 90MPH freeways cruise with blast up to 130 to catch a speeder.

On this note I wonder what the new F150 hybrid/ genset combo penalizes the OLM for an hour of Idling?
Now that many o them are going to be idling overnight to power trailers it will be interesting to see if any comparison can be drawn.
 
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For my cars i go by mileage. 5k intervals i go with. Today noticed my car had ticked over the 5k mark so will be doing oil change now, checked my records and looks like its been 5 years since last oil change due to less mileage from lockdowns. Oil on dipstick is still golden brown and looks like it can go longer. Be interesting to see what the tbn would be after 5 years in the sump. Since its fully synthetic I'm guessing its probably ok.
 
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If you do mostly driving(as most of us do) , as opposed to a significant percentage of idling, you should stick with miles.
 
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