Bob Bell says it's not fair of Max Verstappen to blame all of Red Bull's problems on the Renault engine.
Bell, a leading technical official at the French manufacturer, is referring to Dutchman Verstappen's recent outward and repeated criticism of the customer engines supplied by Renault.
"For Max, it's all about being fast because he's young and in a hurry," Bell told the Ziggo Sport broadcaster.
"He wants to win because he knows he has the potential and he's disappointed that his car lets him down. But he only blames our engine," he said.
"We make no changes to the engines we use for our (works) cars and the ones that go to our customers," Bell insisted. "It may be the installation of the engines that affect the Red Bull cars, or maybe they've just been unlucky."
Red Bull and Renault's fractious relationship will finally end after November's 2018 finale in Abu Dhabi. From 2019, the energy drink owned team will be powered by works Honda engines.