I've run synthetic oil in the car since I've had it - Castrol Syntec 5W-30 (winter) and 5W-50 (summer). Car gets decent oil mileage, pretty steady at about 1500-1800mi/QT. No big deal from my persepective, just put one quart in between changes and do the change when it's down the second quart. I also use Mobil One or Purolater Premium Filters - stay away from the standard Delco and Fram crap.
New Plugs @ 100,000mi Went from Delco Platinums to Champion Iridium's
4 New Coils @ 100,000mi Two were corroded, replaced with better quality Standard (Blue Streak) Coils
New Wires @ 100,000mi.
Good Parts Source: RockAuto.
That's it for the engine.. 113,000mi with only the 100K mile service performed.
Transmission - changes every 50,000 miles, a pair of shirt solenoids at 90,000 miles.
Alternator, Starter, and A/C Compressor all needed replacement between 75,000 and 105,000 miles. Pay the big bucks, have them done by Cadillac service and now they have a LIFETIME unlimited parts and labor warranty (they've already had to do the alternator again)
A/C also has a pipe issue - one of the pipes rubs against the frame rail on the passenger side and develops a slow leak.. easy fix.
Electrical - the only electric problems I've had are with the PW motors. Just go to a junkyard and get 'em for $40 and have em put in when the fail. Power Antenna and Bose music system still work perfectly, all mirrors, seats, etc work fine. The only real bad design defect is the big center LED tailight - there's an outfit in TN that rebuilds 'em the right way for about $150. Did that once 5 years ago and have had no issues since.
Suspension - all original Struts, tie rods, steering rack, ball joints.
Exhaust - replaced Cat Converter at 105,000mi.
Brakes - the rear brakes last forever, the fronts are the weak element. Go to Tire Rack and get a set of Brembo slotted and vented rotors and Green Stuff competition linings.
Tires - I run slightly larger tires than the OEM version, makes a huge difference in cornering. P225/60ZR16 are the OEM size, if you want the ultimate P245/50WR16 Goodyear F1 GS-D3s will fit, although the RH Front will rub just a bit against the plastic inner fender on full LH lock.
Exterior paint (Burgundy) has held up well, and Interior (Black) has no rips/tears just a slight bit of cracking on the driver's side. Make sure you get the windows tinted (3M is a good bet) if you want the interior to last.
Performance - here's a little secret. If you really want a good 0-60 time shift into L2.. the transmission will respond with a nice firm 1-2 shift, enough to light the tires! Car runs 0-60 in the mid 6's, I've got a 1/4 mile drag slip at 14.85 @ 96MPB and it'll easily do 135-140 MPH on the top end (I've read 144MPH)
Awesome car, a 4-door 'Vette, bulletproof Powertrain, decent handling, and great gas mileage (25.6MPG at 74MPH), high 17's mixed/ around town. Cadillac comfort and you can blow almost any non-M BWM off a stoplignt.
Car still has all of the original suspension pieces, radiator hoses, water pump, and mufflers/exhaust pipes. Not bad for 13 years and 113,000 miles.
Next report at 150,000 miles.