McLaren racing director Eric Boullier has admitted his team is unlikely to fight for championships as long as it is an engine customer of Renault.

McLaren will use Renault engines until the end of the 2020 season after ditching its works deal with Honda over the winter. The switch followed three years at the back of the grid with Honda, but Boullier believes McLaren's ultimate aim of fighting for titles is still out of reach with Renault engines.

"I think Red Bull is showing that you can win races as a customer, but I think winning a championship is another level -- you need to have a works team status," he said.

The statement is in line with the thinking of former McLaren boss Ron Dennis, who brokered the deal for Honda to F1 to return in 2015, but appears to be at odds with McLaren's decision to ditch Honda for Renault over the winter. It also comes less than a week after Red Bull decided to switch from Renault in order to take up a works deal with a now-improving Honda for 2019 and 2020.

But Boullier believes McLaren is still better off with Renault power in the short term ahead and admits the team's current failings are with its chassis.

"It's true that this time last year we had no points at all, so obviously we are now in the fight for fourth with Renault and once again, we would prefer to be comfortably fourth, which was one of the targets we had assigned to ourselves," he said. "The car this year is obviously not working exactly like how we expect to be but we are still using this as an experimental experience.

"We want to learn from this car and learn as well working with Renault -- because it's a different partner from last year who we worked with for some years. We have something new to learn; some of the technical options we have not explored yet."