Daniel Ricciardo says Red Bull is unlikely to use the upgraded Renault power unit available to the squad at this weekend's United States Grand Prix.
Renault has brought the modified engine to the Circuit of the Americas as it bids to refine performance but if drivers fit the unit they will sustain a 10 place grid penalty, as per the regulations.
Ricciardo says that the impact of the penalty is not outweighed by the potential gains available from the engine.
"It's available if we want to use it, but obviously that would mean a penalty," Ricciardo explained.
"We've got to understand if it is worth it. The last I heard [the gains are] not massive, so from my understanding is it is probably not worth taking it. We're down such a chunk, I don't think we're going to gain enough.
"If we start from the back, I don't think we're going to make up the ground we need with it. Right now we are less likely to take it. That's about it.
"Hopefully today they [will] tell me something different and we'll find a bigger chunk of horsepower from it, but realistically it's not going to be worth a lot."