Ahead of this weekend's Azerbaijan Grand Prix, the FIA has increased its efforts to restrict teams from attempting to generate a power boost by using oil as fuel.
A subtle oil-as-fuel ploy came to light before the 2017 season kicked off when Red Bull Racing suspected rival teams were using the stratagem.
The governing body subsequently took a keen interest into the matter, monitoring oil usage and chemical composition to ensure that everyone was running within the regulations.
But with potential ways of getting around the rules the FIA has now explicitly informed teams the use of chemicals to improve internal combustion is strictly forbidden.
Marcin Budkowski, head of the F1 technical department at the FIA issued the following note:
"We wish to remind you that, as previously stated in various meetings and re-emphasised in TD/004-17, we consider the use of oil as fuel to be prohibited by the Technical Regulations.
"For the avoidance of doubt, the only fuel that may be used for combustion is petrol, and the only permitted characteristics of that petrol are clearly set out in Article 19 of the Technical Regulations.
"Even though the Technical Regulations do not directly specify the permitted characteristics of engine oil used in F1, we would consider any attempt to use additional components or substances in oil for the purpose of enhancing combustion as a breach of the Technical Regulations."
In a bid to permanently put the problem to rest, the governing body will introduce next year a specific rule addressing the oil-as-fuel issue.
It will call for teams to supply the measurement of the oil level of the main tank to the FIA at all times of an event, that active control valves between the power unit and engine air intake be banned and that teams be limited to a single specification of oil per engine at a Grand Prix.