[Vwdiesel] a couple TDI questions for a new owner!

[Kenneth E. Oldrid]

Hi all.
I saw an unbelievable add on cars.com this week. It was for a 97 passat TDI.
200k on it for $2500! I called the guy in DE that day (wed) along with 15 other
interested people. Well, I convinced him to hold it for an extra $500 on the
price. That he did, and I drove from here (norhtern VT) on wed eve to get it!
People were offering more than I did, but we made a deal and I was on the way.
So, it turns out it's a one owner dealer maintained car in mint condition!
Doesn't seem to smoke except for a little puff when starting. Drove 600 miles
home on the same tank. Averaged 45mpg doing 80+ with the AC on. This thing
screws!
SO, wondering if it is ok/suggested to start running synthetic at this late
age. Records show it was on 5w30 regular oil. Also, do I need use different
driving habbits with a turbo (besides for pasiing everyone)? I heard you need
to let the engine idle after driving to let the turbo cool? I saw a bit of oil
on the bottom of the intercooler; could this be from the turbo?

thanks,
Ken