Follow the Holden Maintenance Schedule Book to do the "mandatory" inspections/renewals etc.
The Tech2 should give you past DTCs if the memory has not been wiped by a previous owner/dealer. This would be an ideal starting point for seeing past issues, and maybe what has been done during the documented/vocalised service history by the past owner/mechanics etc. The quality of repairs may become evident during these checks on the ECM BCM and TCM computers.
I would do the throttle body clean when you have the Upper Manifold removed to do the spark plugs, and visually check the ignition coils for burning, cracking of the rubber insulator, water and oil in the plug tubes etc. Check for oil in the inlet air tract between the MAF and the TB as this will indicate a possible PCV blockage, or general piston ring blow-by caused by worn rings etc. Check the PCV is working properly by checking for vacuum at the even bank clean air inlet. Should get a good suction after about 20 seconds at idle speed.
With the upper inlet manifold removed, with an inspection mirror, check the thermostat housing for seepage/leaks above/at the bell housing area at the rear of the motor. This is an ideal time to replace the thermostat housing if it is leaking or seeping coolant. (Mine seeped coolant).
Also check for any cooling fluid detritus around the heater tap on top of the odd cylinder bank engine cover.
My 2004 SV6, 100,000Kms, suspension has been trouble free, (except for a front sway bar ball joint dust cover failing) but I expect a vigorous check of all rubber bushes and shockers may turn up some wear and tear issues.
Check thickness of handbrake shoes, disk rotors and pad wear etc.
Run a tyre tread depth gauge over the road tyres to see if they are worn from cornering or adverse camber and feathering from toe in/out alignment. Maybe a hint towards future suspension problems.
Check your spare tyre - it may be stuffed if about 9 years old.
There are more cosmetic things like rattling doors which are fixed in most cases by replacing the striker on the door pillar. About $12 per door.
Check the internal hood lining is not fallen away under the front sun visors. Replacement is about $200 or so - mine is due a new one about now.
Serpentine belts are about stuffed if cracks in a rib are about 25mm apart, and most ribs have cracks in them. My belt is original, no cracks as yet, but the car has a birthday coming up so I might replacement it.
They are a nice car, enjoy!
