Second Oil Filter

I have a c-10 and love this engine, 8.5 mpg, 930,000 miles or there abouts on the engine, only add a gallon of oil every 15,000 miles or so.
I also run a harvard bypass filter and only change the oil at around 75,000 miles even then the oil samples say that the oil is fine, I also add a gallon of motor cote when I change the oil.
this is in a century c-112 and before anyone says anything with 930,000 miles and still running sweet with the money I have saved over the years on oil changes and the fact that I have a lifetime average of 8.7 mpg this sweet setup has more than paid for itself.
it also has an auto shift and have only replaced the clutch one time at 750,00 miles

 

Mind you, you know more about this then me. But the last time I looked at the cat engine we have. It had a second oil filter and a small drain on the side and a metal tube going up to the turbo. I believe this is a second (lower micron rated) filter. So it wouldn't hurt swapping in a fresh one.

 

i have a c-13 and i also have that setup just talked with cat last week and they said it was a factory bypass filter was told it would filter about 20% more,he also told that since i run their high efficiency oil filter and change out around 15000,that it would be a waste but i am looking to at least extend out to 20k so ill be added one on my next oil change.i am using the kendall oil that is sold in the flying j and lucas.

 

Thats how it is supposed to be, The filter that screws on there is 1W8845 (Cat number), this is a bypass filter only, kinda like an oil polisher. Most trucks out here run them, but those that dont run them dont have any issues because of it. I think a second filter wont hurt anything but its not a necessity to have it, thats why they dont all come with one from the factory.
If you take oil samples now, why dont you fit a second filter to it for a few oil changes and see if there are any changes in you samples, less soot, etc., if your samples stay the same then ditch the filter and refit the cap. If you do this please report back, would be good to have a back to back comparison to know if the filter is worth it.

 

In the long run it's best to have this filter installed and replaced as needed.

 

I did a little reserch and the 1W8845 is a 5 micron filter and you should get the 30k out of the oil like you wanted. But I would grease the truck at 5-6k instead of 15k. Grease like air for your tires is cheap, parts and labor are not.