From my experience, the oil on turbo Saabs seems to get warm pretty quickly compared to other cars that I know, which I always assumed to be because of the oil flow through the turbo.
However, engine oil only gets really hot when it has some serious cooling to do. The main item cooled by the oil is the underside of the piston crowns, the turbo being mainly water cooled. The pistons only get seriously hot when you are burning loads of fuel. As Mark E said, a constant 90 mph does not really put that high a load on the engine (i.e. require that much power), and toodling around town certainly does not.
I would expect the oil cooler to be hot immediately after a hard run, but in our climate the oil will cool quickly and the thermostat will soon close.
From memory, I've only noticed my oil cooler being hot a few times. The thermostat temperature may be hotter than you think (I can't remember what it is, but a Mark 1 Golf GTi had a 110C stat).
The important thing, of course, is that it does open when you work it hard, but this may have to be harder than you imagine, and in warmer weather.