Stanaway was holding position inside the top 10 just over 20 laps into the 161-lap endurance event when the engine in his Grove Racing Ford suddenly seized on the back straight.
The 32-year-old managed to keep the Penrite Mustang off the Armco barriers and was left disappointed following what was otherwise a promising weekend.
“It was a fresh motor for this weekend so a bit unexpected but it happens, that’s motorsport. Just really unlucky, I was looking forward to that one,” shrugged Stanaway.
“I got a strange exhaust note at Turn 1 and then it started letting go down the back straight and locked up pretty solid.
“I was going pretty quick when it locked up so it was a pretty sketchy slide for a while but luckily didn’t hit anything.”
Disaster for car #26 again at Sandown!
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The stranded Grove Mustang triggered race control to call for the Safety Car, which under new-for-2024 procedures requires drivers to slow to 80km/h within 15-seconds.
That caused chaos on the front straight as drivers hit the anchors at different points.
Will Davison’s Dick Johnson Racing Mustang copped a rear-on hit from David Reynolds, who was in turn hit from behind by Tim Slade.
“The 15-second board came out and everyone just starts slowing down, [but] you don’t need to slow down at that point,” explained Reynolds.
“Then there’s a five-second countdown where you need to go down to 80 kays, I was watching my dash trying to count myself down and I look up and Will was slowing down faster than me.
“So I crashed into him and then I think Slade crashed into me behind, everyone was caught off-guard a bit.
“We’ve got new rules these days with that 80 kay, at least we’re safe crashing into each other these days.
“In the old school we would have slowed down no dramas, but it’s a bit weird these days.”
The Safety Car led to a flurry of pitstops, allowing teams to swap to their co-drivers while taking on fuel and tyres.
There were panicked senes at Matt Stone Racing as Stanaway’s car was delivered to pit lane on a flat-bed truck, momentarily blocking access to the team’s pit box.