Red Bull drivers Sebastian Vettel and Mark Webber both suffered engine problems last weekend at Hockenheim, according to Germany's Auto Motor und Sport.
Webber, who finished an unaccustomed sixth, revealed he had to reduce his speed in the second half of the race because the supply of oil from an auxiliary tank was not working.
"I was happy to just get to the finish," said Webber. "It was our strategy to only show our final package on the very last day of testing. So we were down on kilometres to guard against all those sorts of issues."
Vettel, who finished third after starting on pole, encountered problems between the Friday practice sessions when his high-mileage Renault V8 was replaced after an oil sample was tested.
Vettel had been hoping to convert his pole position into another race win but a poor start saw him squeezed out by the two Ferraris into the first corner. The team's race starts is an area team boss Christian Horner is looking to address.
"They were definitely not the best starts," admitted Horner. "It has happened to us several times this season."
Source: ESPNF1
