Oil consumption?
 

The previous owner used 5w30 oil in my 97 disco I changed over to 15w40 rotella last week... 300 miles later I checked the oil and I was 2qts low and the oil that was on the dipstick was totally black . I don't see any oil leaks and I dont see any smoke coming out of the tail pipe and the headgaskets were replaced last year according to prev owners documentation. Any thoughts on what could be going on would be much appreciated.

the oil being black probably means its cleaning up a lot of the old build up and junk. rotella is good for that being a high detergent diesel oil. you may want to change it again at 500-1000 miles.

as far as the oil being low, who knows. possibly you just didn't add enough when you changed the oil. the rover V8 takes 6.5 quarts which is more than most engines. or more than likely there is a leak. most of us have at least one place on our engines that leaks, seeps, and/or weeps oil.

Yeah it could be cleaning up the gunk the truck was sitting for a year so I'm sure there's some build up. I did put in 6.5qts maybe even a little more and I made sure it was right at the full line. I figured me adding 2qts weekly would be a significant leak I could see but I'll do a more in depth search.

It takes 7qts.
Your gaskets and seals are soaking up the new oil, your oil "consumption" will continue until everything is soaked up and full of new oil.
My truck did the exact same thing, so did my wifes Sedona and my mom's Escape.

Ok I'll just keep an eye on it

Check every day for the first week, don't want a sneaky leak to get past you. Valve cover gaskets need to be snugged up usually (8mm 12 point 1/4 inch drive). Down below the front crank seal can throw it out where the air from fan blows it around, the oil pan with 73 bolts is also a good place, and the ever popular rear seal. Plus those wonderful oil cooler lines. I suppose a peek in the coolant bottle would be in order, can go from head gaskets or the oil cooler inside the radiator.

Hopefully none of the above.

ill take a look at each of those areas this week and check the torque