DD15 engine eating one gallon of oil for every 5000-6000 mile, Please advise.. :(

U may leaking oil under hot conditions,or ur rings may be worn. I don't know how many miles in the truck....Hope u find it.U may just need to tweek the pan,or maybe u need a new gasket....

 

Check oil after truck has been shut down for at least an hour to get an accurate reading, if you check oil with engine hot the engine still has about a gallon of oil in the upper end and if you add oil it will just blow out the exhaust.

 

I wouldn't worry about it. Just add oil. Your only problem you may encounter, if oil is going through exhaust I'm not sure how healthy it is for your DPF. I hope you figure it out. Don't go spending ton's of money, just relax and top the oil off.

 

i suspect you already know you need to find a mechanic you can trust that doesnt just keep throwing parts at everything until you give up or the engine gives up.
you already know where to start if you care enough to use synthetic
clean the engine look for leaks oil anylasis etc etc
280k shouldnt be using any oil
my paccar is on 50000 mile oil changes never added oil at 210000

 

Wow! $40 a gallon? I can get Delo 400LE 5w40 full synthetic at wally world for $19.98 a gallon. And yes, it is an ester based synthetic like Delvac 1 and Amsoil. But that being said, I use synthetics in some applications, but for my big truck, I have run tons of oil samples on both synthetic and conventional and have not seen any appreciable differences in wear numbers, TBN depletion, soot loading, etc to justify using synthetic in the engine. I went back to standard Delo 400LE 15w40. Even mpg numbers didn't change enough to justify using synthetic. If it makes one feel all warm and fuzzy to use synthetics in a class 8 truck, by all means have at it. But it is going to be extremely difficult to prove that you will extend the life of an engine using synthetics. And unless you have real oil sample results showing a major improvement, then you have nothing to substantiate that decision. Even Delo, in its testing, has shown that in the DD15, they have taken standard Delo 15w40 to 70,000 mile oil change intervals with no evidence of additional wear in the engines when they tore down a few of them to have a detailed look.

Go over to the BITOG website and have a back and forth with a professional tribologist (oil specialist) there that goes by dNewton. He can give you better information than I can that using synthetics, especially compared to oils of CI-4+ and CJ-4 category, is more often than not, just throwing money down the drain. Only if you have a very special application or operate in some real nasty conditions does he think you would benefit from using synthetics. The oil marketing folks are having a good time of it convincing everyone that they need synthetics. They are good, don't get me wrong. But only needed in special circumstances. For transmissions and diffs, I always use synthetics. In an engine? Out of all my diesels, only one is actually on synthetics.

 

To the OP
For now i would use the truck as is.
Cowpie gave you a hint as what you can do.
Which would be to take an oil sample and have it analysed.
If anything like rods,pistons in the engine has worn out premature,the analyse will show that.
That analyse will narrow the search area.(it is the cheapest diagnostic tool there is,besides being the best)

I do agree with Cowpie,synthetic oil isn't worth the money.
A good mineral oil and a few analyses will tell you the best interval time.
I do advocate a spinner oilfilter.

Let us know what happens.

 

Have an oil analysis performed, load the truck, and go to trucking. If the test comes back OK, good. If not, fix problem. But I would run it.