I'd change regular every 5,000 miles and synthetic at 7,500 miles. Anything less than that is too early IMHO. Synthetic could go up to 10,000 miles if you only do highway driving.
Either way, I'd stick with Mobil 1 15W-50 Synthetic for summer and Mobil 1 10W-30 Synthetic for winter (up north).
1988 Mercedes-Benz 260E (W124)
Clear Turn Signals and 1994/1995 Taillights
16" x 7J 8-hole
Michelin Pilot HX MXM 205/55WR16
1997 Mercedes-Benz E420 (W210)
Michelin Pilot XGT Z4 P225/55ZR16
1997 Mercedes-Benz C280 (W202)
Michelin Pilot SX-GT 205/60VR15
[This message has been edited by DSinger (edited 11-02-2000).]