As expected, the unpredictable weather made conditions difficult for the drivers in the 2005 Belgian Grand Prix. Following intermittent rain in the morning, Red Bull Racing duo David Coulthard and Christian Klien started the race on intermediate tyres. As the track began to dry, many drivers, including David and Christian, took the opportunity to change to slicks when the safety car came out on lap 11. But, struggling for grip, they were forced to re-pit and return to the intermediates. Including high-speed corners and sudden elevation changes, the Circuit of Spa Francorchamps is one of the most technically demanding tracks of the year and, on lap 18, David Coulthard's engine showed the strain. Unable to continue, the Scot was forced to retire, while his team-mate Christian returned to slick tyres and finished the race in ninth position, narrowly missing out on points.

David Coulthard: That's the first engine failure we've had since December. We have to accept that these engines are stressed and occasionally one will have a fault; but obviously it's too early to know what exactly caused it. We took a punt on the dry tyres as we thought the safety car would be out for a long time, which would give the slicks a chance to get up to temperature. As we must now use one slick tyre for the race, it has to be a hard compound to last the distance. That makes it more difficult to get it into its operating window in terms of temperature; so putting a slick tyre on a damp track doesn't work. On the other hand, intermediate tyres on a dry track will overheat so you end up with this no-man's-land area where no tyres fit. It's very entertaining for the crowds, but it's dangerous for us because while the wet tyres are burning up, the slick tyres, as we saw, don't work in these conditions.

Christian Klien: My start was really good and I made up three places on the first two laps. The track was wet, but as it was drying we changed to slick tyres when the safety car came out. However two laps later, I came back in and changed back to the intermediate tyres. The car was too uncontrollable on slicks on the damp surface and basically, we changed too early. I went back to slick tyres at the end of the race when the track was drier and ended up in ninth place. It's pretty disappointing as without mistakes, we could have easily scored some points here.

Christian Horner, Sporting Director: The cross over point at which we could change from intermediate to slick tyres wasn't very obvious. I think we timed Christian going onto slicks near to the end of the race at the right time, but, by then, we'd given away too much track position. When we went to slicks earlier in the race, David immediately said it was still too wet and came back in along with Webber, Trulli and a few others who had also tried slicks. Christian did an extra lap before coming back in, which cost him around 25 seconds and probably lost him a point. But, he drove a good race and didn't make any mistakes. When we put him on slicks the second time, he was one of the quickest cars on the track. Unfortunately, David suffered the first engine failure of the year, it's disappointing but to get to the 16th race of the year without any before is pretty good going.

Chris Jilbert – Cosworth F1 Race Engineering: Cosworth suffered it's first race engine failure of the 2005 season in David's car during today's Belgium GP. There was no significant warning on the telemetry prior to failure. The engine was on it's second event of the demanding Monza/Spa combination, but the duty cycle was actually not as severe as predicted given the weather conditions this weekend. We will now check the logged data & inspect the engine to determine the cause of failure. This is a disappointing result given Cosworth's excellent reliability record this season, plus the fact that David would potentially have been able to add to his points tally today.