Stationary diesel motors, as any other diesel or gasoline engine, contain a given amount of oil which depends on the motor size, power, rpm etc. The oil has to be changed according to the engine manufacturer instructions. In the case of mobile engines (cars, trucks etc.) the gap between changes is given in "so much" kilometers (or miles), i.e., the oil has to be changed when the truck has run "so much" kilometers. In the case of stationary engines like yours, the gap is given in "so much" hours of operation, i.e., the oil has to be changed when the engine has run for "so much" hours.
The kind (viscosity etc.) of oil is also specified by engine manufacturers. On the instruction manuals they use to list several oil brands and types that satisfy their requirements.
You should strictly follow the manufacturer instructions in order to prevent any lubrication problem and, if it is the case, do not loose the manufacturer guarantee.
Giovanni S. Crisi
Sao Paulo - Brazil

That does sound like alot, we have a smaller rig and I'd "guess" that it only uses about a one fifth of what you are describing.

Sparky: At 700 hrs your welder is not even broken in yet in my opinion, any new motor will use or lose some oil for a while, and deisels always use a little bit of oil anyway. Just about every welder I've used was either a gas or diesel driven machine, I used 2 brand new Miller diesels bought at the same time and they both used about a quart in 40 or 50 hrs for about 1200 hrs, after that they used about a quart every 120 hrs. The gassers I used and the one I have now(SA200 built in 1963) all use about a quart every 150 hrs, depending on the rod I'm using, and a heavier rod will make the motor work harder, so it will use more oil. I rebuilt 4 motors for welders and they all used oil for a while, shucks Iwas about ready to tear 1 of them back apart to see what I messed up on til I figured I'd give it time. So I ran that thing like a racehorce for about 2 months finally it settled down, guess what I bought it and I'm still using it.
However, check to see if any of the gaskets are leaking, If they are tighten them up a bit and maybe add some engine sealer to make the gaskets swell up a bit, it works trust me just get some that's made for diesels. Also check to make sure it aint blowing it out the stack, if it is there is an internal problem, and should be looked into, if it is just burning it a bit give it some time it should settle. All that being said, that thing should have some warranty left on it, maybe have the dealer take a look and see what they say, just don't let em BS you. But I really don't think a quart and half every 200 hrs is a big thing unless it's blowing raw oil out the stack. Hope this helps, have a good day J Krout

My thanks to all who replyed. I spoke to the dealer rep & he also said check the stack on the machine so I did. Just a little black soot. One of the fellows I' ve worked with had the engine go out on this same type machine at around 2000 hrs. Presumably it was because of dirty air filters. Lots of dirt flying on those pipeline right-of-ways. I should mention the machine is very good on fuel ( less than 2 litres/hr ).