if any mechanic told me that 1 gt oil is normal for a 3.5 diesel to use in 1200 miles i would avoid him for sure.
you are at the stage of bent rods and it will get worse pretty fast.
you dont have to believe anything that has been written about these engines here in the forum, but please go read the threads.
its a money pit now, make some wise choices.
larry perkins lou ky
86 old cars(3 are 1991 350 sdl)