Oil leak ford mondeo mk3?

I have a ford mondeo mk3, over the last few weeks I have had to keep on filling it up with oil. I have to add about a ltr every 100 miles. I can't see a leak and no oil patches and I have no smoke coming out the back. I'm also using alot of coolant i'm guessing cause when the oils low it gets hotter.

Any ideas

Trade it is as soon as possible.

If both oil and coolant are going then it sounds like the head gasket has failed. The engine is on borrowed time and is at risk of overheating if the coolant level suddenly drops, or total failure if the oil level drops to the point where the oil pressure disappears. By the time the warning light comes on the dash it's usually too late.
Needs to go to a garage to get checked out.

If that amount of oil was being burned then there would be smoke - more than 1 litre of oil added per 1000 miles is excessive and you are adding 10 times that.
If it is not being burned and not ending up in the water then the only alternative is a leak as they are the ONLY places it can go