Oil being lost??????

How about giving us a clue what type of vehicle it is and the mileage?! If it's an older vehicle with a good 100,000 miles on it you're best off just adding oil as it goes down on the dipstick. try to not let it go more than a half quart down. Keep changing the oil and filter every 3,000 miles. Using a heavier weight oil will not stop or even slow down the leak or burning of the oil. If it's a GM vehicle with a 3.5 liter motor the valve cover gaskets leak all the time and should be replaced as it's a fire hazard. The oil pressure warning light sending unit is another place that the oil leaks out enough when the unit is bad to cause a quart of oil loss in 3,000 miles If it's not a leak I'm surprised the spark plugs don't get fouled and cause misfires that would turn on the CEL. A motor burning oil is caused by not changing the oil and filter every 3,000 miles and letting the oil turn black before changing it. Bottom line is keep checking and adding oil once a week or the alternative is another motor.

You are a mostly wise person. You are someone who actually checks the oil, rather than running the engine until the oil is all gone and the pistons seize.

Find a parking spot on nice, clean concrete, preferably somewhere not owned by you but also where the owners will never catch on to what you are doing. Park your car there for a day or three without moving it. Look underneath to see where the oil drips. That'll tell you where the leak is, sort of.

If you don't have handy concrete, you might put some newspaper underneath the car, weighted down by stones. Choice of Daily Mail or the Times is up to you. Hint: The on-line versions will not work for this. Except maybe for the Grauniad.

If you find the source of the leak (something your mechanics should have been able to do) then you'll need perhaps a gasket replaced. Use a better mechanic to do the job, not either of the previous two.

If there is no obvious source, then you need to have the engine rebuilt. That involves new piston rings and possibly reboring the cylinders. It is usually quicker and cheaper to buy a rebuilt engine instead.

On the other hand, rebuilding an engine is a job within the scope of what an amateur mechanic might possibly be able to accomplish. There are oodles of YouTube videos and they'll cover most of the major blunders. Your car will be unavailable for weeks as you get everything sorted out.

The expense of rebuilding or replacing the engine might not make sense for your particular car, in which case you simply continue to add oil until it's time to get a better car. You always did want a better car, right?

oil additives doesnt cure engine oil from burning or dissapearing. ,on cold start ups if the tail-pipe emits blue smoke than this is normally caused by either worn piston rings or valve stem oil guide seals.. the most common cause is stuck oil control rings. Generally the stuck oil control rings are the result of excessive oil on the cylinder walls and this excessive oil can come from the PCV system and/or the AFM pressure relief valve in the oil pan.