The Frenchman, 27 - Renault's official test driver - refused to confirm that he'll fulfil Robert Doornbos' role beyond the European grand prix.
"I'll see what the car's like," he told ITV, "what the team is like. We'll see. It could be bad if the (Jordan) car isn't perfect."
Another concern, for Michelin at least, is that Montagny's test might allow Jordan (and Ferrari) tyre supplier Bridgestone a useful insight into the test driver's experience.
"I'm not going to ... ruin my relationship (with Michelin)," Franck insisted. "I'm professional, I'll help Jordan, but I'm still a Renault driver."
The Nurburgring paddock, meanwhile, strongly suggested that Friday's drive is a trial to a possible 2005 race seat -- in Tiago Monteiro's spot.