by the car manufacturer. the radiator has been replaced. I was using 89 because i rarely pushed the car, drove it at 55 like an old lady, even though it was Turbo and Volvo specifies 92 octane on the Gas Cap.

Did I goof? By using the 89 octane? I figured since I was driving Like an old lady, I didnt run the risk of detonation and didnt need that hi Octane. I may have been wrong.

The radiator was replaced 5,000 miles ago. I'm going to change the Thermostat this afternoon. And get some new plugs...

Finally the NOx figure. I might not have got the units right but I did get the ratio right; it was 2300 vice 1199 passing...

The car passed fine two years ago and has been very well maintained...