For all 4 and 6 cylinder single cam gas engines 1984 to 1992. High oil consumption is becoming such a big problem with these engines and it is usually related to valve stem seals. And yes, it is very common and the number one reason for these good engines burning oil. The seals harden with age and become very brittle. When that happens they lose all their ability to seal engine oil from leaking down the valve stems and into the combustion chamber.
Problem & Solution
Common among these chassis:
Valve seal replacement in a shop is very expensive. It is not a difficult job, but requires the right tools and EXTREME care. If you end up dropping a valve down into the engine you will cry for days! Not only will you need to use compressed air to keep the valves closed, but you will also need to rotate the engine so the corresponding piston is up on T.D.C. (Top Dead Center) when working on a particular cylinder. The procedure must require you have a compressor on hand, a special adapter to the spark plug hole, a special spring compressing tool, and know how.
Until you are able to replace the seals, I recommend you use engine oil saver to increase the viscosity of the oil and to slow down consumption. You may have to change spark plugs more often than normal and there is only one spark plug that does well when you are dealing with a 190E or 300E with this problem. See related products.