Diesel oil on 2004 Dodge Ram 1500 4.7

If the cause of oil burning is sludged up rings, it may clean them up and they'll seal again. But diesel oil alone does not have enough lubricating properties to be used entirely in place of motor oil. There's better engine flushes on the market but they can knock loose a ton of sludge and clog up the pump screen and return journals on a high mileage engine. In the old days they used transmission fluid, which is a strong solvent. Flushes are used for five minutes at idle speed. I'm not sure this is a good idea. Marvel Mystery Oil works, one quart added to the oil. On old engines I would do frequent oil changes until things get cleaned up a little at a time. Might take a year and five oil changes. Remember, synthetic oils don't oxidize into sludge.

My truck have 280000 miles, what kind of oil would you recommend?

Did he mean diesel fuel or 15W40 diesel motor oil?

Ooops. I was thinking diesel fuel oil not motor oil. I read that wrong. F_O_R is saying put Diesel motor oil in the crankcase and I agree. That Diesel motor oil is 15w/40, a heavier grade, which will reduce oil consumption due to burning. Made especially for diesel engines.

I was clarifying the question. Diesel motor oil has a lot of detergents in it. If you want an engine flush I would buy one made for that purpose and use it per the directions.