Why would a 1993 Plymouth Voyager be burning oil?
Well, it is normal for older vehicles to develop some leaks
(small) and for most cars to burn oil (1/2 qt every three months).
However, it sounds like you should really talk to your oil changer
and ask them what oil they are using and what the old oil looks
like. If it has water, coolant, or has a big leak you need to look