What type of oil do you use in your GT? Conventional or Synthetic and how long do you go between changes with ordinary driving habits?

NasaGT said:Motorcraft 5w20 Synth Blend, every 3000 miles. First change at 500, then 3000, and I just did the 6K change. I'll switch to Mobil1 if they every come out with a 5w20.
Is that the synthetic version? cuz if it is don't they say you can run it for 5-7,000 miles before next change?AdRock said:Amsoil 7500 brand 5w-20, change it religously every 3k miles. I use the Motorcraft filter.