Mercedes has "a few balls in the air" over F1 engine reliability

While Mercedes hopes to get through the rest of the season without needing a fresh power unit for championship leader Lewis Hamilton, there are growing concerns that it may have to do so and take a grid penalty.

The precarious situation the team is in was highlighted over the Russian Grand Prix weekend when a fresh engine Valtteri Bottas had fitted in Italy hit trouble and had to be removed.

That forced another power unit change, which dropped the Finn down the order on the same weekend that Williams driver Nicholas Latifi also took a grid drop.

While Mercedes is awaiting analysis of the Monza power unit to find out if it can be used again, team boss Toto Wolff conceded that things were a bit unsettled at the moment regarding its engine prospects.

As well as dealing with this season's plans, Mercedes needs to be committing to its 2022 project when engine specs are fully frozen.

"That's why we're having a few balls in the air, because you need to have the right balance between making sure that you really sort out all the gremlins that you have in the power unit, not only for this year but also for next year's power unit," he said.

"Definitely, we are in a phase of assessment on how to continue the season in terms of power units."

Speaking over the Russian GP weekend, Hamilton said he was mindful of not stressing his current engines too much in a bid to try to help the situation.

Lewis Hamilton, Mercedes W12, Sergio Perez, Red Bull Racing RB16B

Photo by: Mark Sutton / Motorsport Images

"Of course I lost one engine. Valtteri's had several," he said.

"And there's been others that Mercedes have seen up and down the paddock.

"So right now, I'm trying to treat my engines, the ones that we put in, with the absolute care when I'm driving, in terms of how much I'm gassing it, how much just revving the things, revving the nuts off it, really trying to minimise the laps that I do."

Wolff said that the Bottas Monza unit would be inspected before the next race in Turkey.

"We want to understand the engine's performance, and that has given us some question marks," he explained.

"At the moment we just take it one race weekend at the time and reassess the performance of the power unit, and then that's it."

Asked if engine reliability was now Mercedes' biggest concern in the title chase, Wolff said it was clear that the team could not afford a failure in a race.

"It's always reliability versus performance, it's always a fine line that you need to get right," he said.

"DNFing, obviously, is a no go for the championship and nobody, neither us nor our competitors, can afford a zero points race weekend."