oil consumption

I don't have a Cat in my fleet. However if there are no leaks anywhere the only thought that comes through my mind is you engine is piston ring wear or possibly blowing by your turbo.

 

or it's blowing out the stack

 

Every Cat I ever drove except for a couple needed a gal.of oil after the first 8000 mi.or so on a PM and another gal after 3000mi or so basically every 3 or 4 fuel stops they would need after that first 8000 mi.

 

mine never uses oil,,,,,it's an 03

 

You should be very thankful.I only drove a couple that were like that but they were built in '05.

 

how many miles and has the eng been overhauled, if so how long ago? if its not leaking, its blowing out the stack or out the blowby tube. might be time for a overhaul.

 

Oil use, after the oil is changed, you want to check it every day, write it down, When the oil is changed, you want to take it to a shop and have then put it on there computer at the end of the list of parameters, is the oil pan fill amount. With that you want to have the dip stick checked, You can call Cat and they can give you the amount also. have the serial and arrangement number.
If the oil level stays good for say 5,000 miles and then starts going down it is rings. If it goes down steadily it could be valve guides or turbo. Cummins makes an oil dye P/N3376891 you add it to the oil it will not hurt anything and the instructions are on the bottle how to test the turbo. If you have oil dye after the turbo you remove it and if there is oil, and dye in the manifold, you have decisions to make.
If you remove the valve covers and you have carbon around the valves it is guides. You will also have blow by, at high idle and usually use lots of oil if you idle it a lot.
Just a thought!

 

ditto rings-valve guides or turbo if its rings a good chance you will have some blowby same for the turbo.

 

2 gallons of Lucas is too much. That is probably what is burning off. That much will make the oil way too thick, and hurt fuel mileage. 1/2 gallon would be more than enough.