Oil life?? Time vs. mileage ....

I change my oil in my classics when I get them out after the winter. I put less than 3000 a year on them. The newer cars with fuel injection and overdrive are a different game. First, fuel injection runs cleaner. Second, the overdrive takes about 500 rpms off every minute of highway speeds. That is 30,000 less revolutions every hour, or approximately every 60 miles. Now picture the revolutions overdrive saves in a few thousand miles?! I change my oil in my FI overdrive vehicles every 5000 miles. This happens in approx. 3-4 months