Red Bull has elected not to use the upgraded Renault engine for the opening day of practice at the United States Grand Prix, but could still bring it into play for qualifying.
The Milton Keynes-based team has been evaluating whether or not it was worth taking a grid penalty to use the new specification engine in exchange for the extra performance it brings.
Renault has used 11 of its 12 development tokens to make a number of changes to improve power of the internal combustion engine.
However, there was some scepticism among the team about whether or not the performance gains would justify starting further down the order.
Daniel Ricciardo had suggested ahead of the weekend that it was unlikely it would be raced.
"It's available if we want to use it – that will mean a penalty though," he said. "So we have to understand if it is worth it.
"It [the gain] is not massive, from my understanding, so it is probably not worth taking it. I think we are down such a chunk that I don't think we will gain enough initial time to make it up.
"So if we start from the back, I don't think we will make the ground up we need. Right now we are less likely to take it – but hopefully today they will tell me something different and they have found a big chunk of horsepower."
Motorsport.com has learned that with bad weather hitting the opening day of running, a decision has been made not to bring the engine in to play yet because of the difficulties in getting much-needed mileage on it in dry conditions.
If the weather improves for Saturday, then there is a chance that it could be used, but a decision on that will only be taken later.