I didn't see this thread earlier. Probably too late to stop OP from switching from regular to synthetic after 63K miles on regular. From what I have read (only- no experience), the molecules in the synthetic oil are smaller than the regular oil. After running for a period of time, the seals become worn to the point where the oil molecules provide the actual seal. If you change to an oil with smaller molecules, you may experience leakage. Again, this is only what I have read and I have no links. Just something I read somewhere and logged in the back of my mind for future reference.
If you are starting the engine and run it for over a half hour, so that it gets hot, just about every time you use it, you can probably go a lot further, on average, between oil changes. Even if you don't do that, if you make a long trip of less than 6K, you should be able to do that unless you go ten miles stop, cool down, do ten more, etc. Then change the oil at the end of the trip.