Just read the Toyota preview of Malaysia and even though I've bagged Toyota for their lack of performance over the years I respect them highly for opting to stick with the rules and not exploit them like BAR and Ferrari did. (Sure the FIA should fix their rules but it is good to see teams playing fair too!)
There also seems to be a gentlemans agreement regarding this
In the Q & A part this is what Luca Marmorini said
Is the new engine regulation strict enough in your point of view?
There is still a grey area in the 2005 engine regulations, whereby a driver can come into the pits before the end of the race, effectively retiring a problem-free car, and then be permitted to change the engine for the next race.
What is Toyota's opinion on such loopholes?
Toyota is against the existence of such loopholes in technical regulations. Toyota fully accepted the spirit and intention of the new two race, one engine regulation. We gave the chance for the team to run in all four free practice sessions in Australia, not only because it is important to learn the car's behaviour at the track, but also because our participation in all sessions over the weekend is part of the F1 show. Even though our drivers did not score any points in the race, we decided to pass the chequered flag out of respect for the spirit of the new rules. This obviously increases the chance of having an engine failure in Malaysia, but this is what we understand by the concept of racing.
Is this why Ralf Schumacher's engine was not changed after qualifying in Australia?
Yes - Ralf's qualifying was massively negated by the bad weather and left him near the back of the grid. It would have been easier to change the engine in those conditions with a comparatively minimal penalty, but to do this, especially in the first race, is not acceptable in our opinion. During the course of the season, we may change an engine if there are doubts or issues technically, but we should avoid it wherever possibly as part of the gentleman's agreement that was accepted before the season started.
Well done Toyota