Hi all...need some advice here. I just picked up a 2000 Buick Century Limited with 87k for my sister. The car is an original owner vehicle...middle aged couple from Florida (no rust!). The vehicle has been pretty well maintained (including replacement of the LIM at 72,000 miles)and the engine is quiet as a church mouse...interior is mint and it has new tires. I'm taking it to my mechanic this weekend to have it "gone over" and intend to do a pan drop service for the transmission. From what I'm reading on here, some believe there's little advantage to adding a synthetic fluid for this type of service? I really want to replace the pan filter and limited $$$ preclude a flush AND pan service. My plan was to replace the 7 quarts or so that this will drain with Amsoil or Mobil 1 ATF. Is there any advantage to using either of these synthetic ATF fluids over DexIII if I'm not doing a total exchange?