I am going to change the oil in my 1992 Lincoln Towncar. It has been in there since the first of 2008. It hasn't been driven that much, maby just 500 MI It has Carstol 10w-40 in it, because it burns thin oil. Is two years to long to leave the old oil in it? It is going to be driven ALOT more from now on __ maby 60 mi a day. Or.......is the oil still ok?