No offense guys and especially OP-you can add a quarter of a quart or even a whole quart of many types of oils found in your local pep boys. There are both castrol and mobil 1 synthetics that have a close enough spec for an occasional usage. castrol 5w 50 for example. You could add an entire quart to the other 8 quarts of the TWS and there would be zero difference in ability to perform.
So while I obviously am pretty strict with frequent maintence and proper fluids, there is a point where being overly stringent just is silly.