While team boss Christian Horner has talked of positive progress in negotiations with Ferrari to land a customer deal for 2016, the energy drinks giant made clear on Tuesday that even remaining in F1 is far from certain.

In fact, in an editorial written on its own website Speedweek, it suggested that company owner Dietrich Mateschitz and his motorsport advisor Helmut Marko were edging closer a decision not to continue in grand prix racing at all unless certain guarantees were met.

Although there were no direct quotes from Mateschitz nor Marko on the specifics, the appearance of the strong story on Red Bull's own media platform indicates clear approval of its stance.

The team and energy drinks giant has used the Speedweek platform several times this year to get its messages across.

Quitting F1

The story said: “For those among us who have listened closely to what Red Bull chief Dietrich Mateschitz and his motor sports consultant Dr. Helmut Marko said recently and who interpret it correctly and put together one and one, a clear scenario emerges: Red Bull Racing and Scuderia Toro Rosso will pull out of Formula 1 after the 2015 season.”

In reference to the prospect of a customer engine deal, the story added: “Red Bull doesn’t want to have customer engines that have 30 to 40 hp less and can be manipulated by the constructor in case of the customer team endangering the works team.”

Then in perhaps what was the clearest message of all: “Red Bull would like to continue in F1 only if Ferrari is willing to provide true works engines that are on the same level as the engines of [Sebastian] Vettel and [Kimi] Raikkonen.”

Not customers

Mateschitz has been clear since the start of the year that Red Bull would not continue in F1 with a customer engine deal.

Hopes of a Mercedes deal have fallen through, and Ferrari's negotiations have yet to reach fruition – and there is of course no guarantee that the Italian manufacturer will want to provide Red Bull with exactly the same power units.

It is unclear also too how Ferrari will react to effectively being held to ransom over giving Red Bull an engine deal that risks its own competitive position.

In the Speedweek article, Mateschitz was quoted as saying: “As a customer team you will only get an engine that is good enough to take away points from their immediate rivals. But this engine will never be good enough to beat the works team.

“With such a customer engine we will never be world champion again. And if that’s the case we lose interest.”

Toro Rosso out too

Although Red Bull's concerns about not fighting for the championship with a customer engine may not be as relevant for Toro Rosso, it has also been made clear that Mateschitz would see no point in keeping that team on the grid either.

The article added: “A partial pull-out with Toro Rosso remaining in F1 is off the table now, too.

"Why should Red Bull want to develop talents like Verstappen and Sainz when there is no possibility to have them make a step internally in the footsteps of Vettel, Ricciardo and Kvyat?”