McLaren's upcoming upgrade to Renault's B-spec engine must be well-timed insists team boss Andreas Seidl, or the Woking-based outfit will face unnecessary grid penalties.
Renault introduced its latest engine evolution in France, but Daniel Ricciardo was the sole recipient of the new unit at the works outfit as teammate Nico Hulkenberg was keen on avoiding a grid drop.
McLaren took a similar stance, electing not to bolt the new engine on to Carlos Sainz's MCL34 given the fact that the Spaniard's has already reached his three-engine limit, while a change for Norris was deemed too early.
McLaren now needs to work out for both its drivers when it will consume its upgrade, and a change could come as soon as this weekend's Austrian Grand Prix, a venue that underscores sheer power output.
"It is still something we are working out at the moment," Seidl said.
"We have to collect the data again after France, and then we have to work out our plan.
"And especially what does it mean in terms of penalties until the end of the year with the different scenarios that are around."
McLaren's dilemma centers more specifically around Sainz and figuring out the right moment - or rather the least impacting opportunity - to hand him a fourth power unit.
"As soon as Carlos is going for the upgrade then we get the penalty, because it is the fourth one. So we need to figure out now when we do that," Seidl added.
"In the end, how the regulations are, you need to make a plan of how you’re going to use your engines throughout the season in terms of the modes, mileage and so on to avoid penalties.
"We got the engine delivered from Renault, which is good and encouraging to see that they keep bringing steps.
"But again the plan for us was that it was better not to use it yet, simply to minimise the number of penalties that we would get until the end of the season."