While McLaughlin and race leader Jamie Whincup continued to the pits at speed, Coulthard slowed so much that he was well over 40 seconds slower than his team-mate on that lap.
However, Coulthard still dropped to 10th anyway, behind nine cars which also pitted under that Safety Car, after his crew performed extra work which included raising the bonnet of Car #12.
He claimed that a race-long overheating issue, and uncertainty as to where the incident was, was the reason for the slowdown.
“I was told on the radio that I needed to take extreme caution,” Coulthard told Speedcafe.com.
“My engineer at the time didn't know where the incident was (and) I had an overheating drama which I was battling with as well.
“But just to slow down and things like that, I was told to by my team.”
It was confirmed that the car did take on water to appease rising temperatures.
Roger Penske also batted away a suggestion that Car #12 had been sacrificed to maximise the team's chances of winning the race.
“I'm not sure that made the difference of who's going to win the race,” he said.
“For me, we can look at it and talk about it but it's secondary as far as I'm concerned when you think about what happened at the end.
“Everybody had a chance. When that was all over, the two top guys up there had a chance to duel there at the end.
“The outcome was obviously what we wanted.”
Coulthard and co-driver Tony D'Alberto were ultimately classified in sixth position while McLaughlin and Alexandre Premat claimed the outfit's first Bathurst victory in 25 years.