Audi Junkie,
When I used to help friends service their Vauxhalls (re-badged, British-built Opels) in the UK, I used GM Genuine Long Life Red Coolant on every application. Pre-2001 models used blue coolant, and years before that it was traditional green coolant. The red stuff is recommended for up to 5 years/60,000 miles, whilst the blue/green coolant had a service life of 2 years/25,000 miles. The red coolant was also backwards compatible with pre-2001 models.
The blue and green coolants had mono-ethylene glycol (MEG) corrosion inhibitors, the red coolant comprises of Organic Additive Technology (OAT).
I don't know what the equalivant would be State Side, but the GM part number for undiluted GM Genuine Long Life Red Coolant is/was 93165162 (unless it has been superseded). Hope this helps somewhat.