Team boss Christian Horner has always rejected the speculation on the basis that engine manufacturing is not a "core competency" of the energy drink-owned outfit.
But many thought Thursday's news of a collaboration with the British luxury carmaker Aston Martin was a sign that Red Bull's search for an engine partner may be over.
"Unfortunately Aston Martin don't have an engine we can use, although a V12 would be nice," joked Horner, whose team are instead pushing ahead with a Tag Heuer-rebranded Renault engine in 2016.
But that is just a one-year contract.
And so rumors are swirling that, now with Aston Martin's help, Red Bull could push ahead with an accelerated program to make its own F1 engine.
Auto Motor und Sport is even dropping a name that might be connected with the Red Bull-Aston Martin F1 engine project: Alex Hitzinger, fresh from Porsche's Le Mans foray, a former Cosworth F1 chief and no stranger to Red Bull.
According to the well-known former Renault F1 driver Jean-Pierre Jabouille, however, losing Red Bull as a customer would be a blow to the French carmaker.
"It was important for Renault to keep Red Bull as it helps them to assess how good their chassis and drivers are," the 73-year-old Frenchman told L'Equipe.