Montmeló (Spain) (AFP) - World champion Lewis Hamilton shrugged off an uncharacteristic engine failure in his all-conquering Mercedes on Thursday, pledging to restore order when pre-season Formula One testing concludes Friday.
Hamilton only completed 14 laps before his afternoon run at Montmelo came to a premature end after an oil pressure problem shut him down.
"I only got 14 laps in today, but during those 14 laps, everything was feeling fine," said Hamilton who will aim to equal Michael Schumacher's all-time mark of seven world titles this year.
"Rather than looking at the negatives, we've discovered some things we need to work on, and we'll keep pushing hard to resolve them and keep working away.
"I'm looking forward to being back in the car tomorrow morning and adding to the mileage we've already achieved."
Teammate Valtteri Bottas, who edged Hamilton for the fastest time in last week's opening three-day session at the same track, was seventh quickest Thursday.
"It's frustrating to spend half a day in the garage," admitted Mercedes technical chief James Allison.
"But we worked well with Valtteri in the morning. With Lewis in the afternoon, we still got some very useful data and we are reassured to see that, in turbulent conditions, the car always has a good rhythm."
Four-time world champion Sebastien Vettel was the fastest man on the circuit in his Ferrari in 1min 16.841 sec off an energy-sapping 145 laps.
The German was the only driver below 1min 17sec despite spinning off at one stage.
However, Vettel wasn't reading too much into the times.
"The weather conditions were difficult, the most complicated of the five test days, with a lot of wind," he said.
"It makes today's results not very representative."
Pierre Gasly in an AlphaTauri and Racing Point's Lance Stroll filled out the top three.
Pre-season testing concludes on Friday with the world championship season getting underway in Melbourne on March 15.
Thursday test times:
Sebastian Vettel (GER/Ferrari) 1:16.841 (145 laps), Pierre Gasly (FRA/AlphaTauri) 1:17.066 (139), Lance Stroll (CAN/Racing Point) 1:17.118 (130), Nicholas Latifi (CAN/Williams) 1:17.313 (160), Lando Norris (GBR/McLaren) 1:17.573 (113), Max Verstappen (NED/Red Bull) 1:17.738 (31), Valtteri Bottas (FIN/Mercedes) 1:17.985 (47), Esteban Ocon (FRA/Renault) 1:18.013 (37), Kevin Magnussen (DEN/Haas) 1:18.225 (111), Alexander Albon (THA/Red Bull) 1:18.393 (61), Daniel Ricciardo (AUS/Renault) 1:18.395 (59), Antonio Giovinazzi (ITA/Alfa Romeo) 1:19.670 (92), Lewis Hamilton (GBR/Mercedes) 1:22.425 (14)