I have had good blackstone reports on my 98 volvo N.A. using Penn YB dino and 7k OCI's. I thought I would stretch a 10K OCI using synth. The volvo burns 1 qt. per 2000 miles and I am wondering if at the 8K mark if it makes any difference if I use synth to top it off or if dino would make a difference. I have a bunch of dino, which is why I am thinking of using it as the final top off to get me to 10K. Is this short sighted?