Guys I need some help making up my mind on what to do. I will be changing my oil in the next week or so and need some good opinions. I have a '98 Monte Carlo with the "beloved" 3.1V6 in which I have been using Schaeffer's 10w30 blend for quite some time now. Problem is I only have 3.5 quarts of the Schaeffer's and I don't want to travel to buy any until the GF-4 comes out later on. As most of you know this is a 4.5 quart capacity engine. What quart of oil would be the best to add to the Schaeffer's (remember winter's almost here) until I can get more Schaeffer's?? Thanks.