Rob Collard took his second win of the weekend in the second BTCC race at Knockhill as he once again headed a 1-2 for the eBay Motors team.
Starting from pole after his race one win, Collard led from start-to-finish for a comfortable success, breaking the lap record en-route to his second victory of the afternoon.
Onslow-Cole followed him home in second place while an unchanged podium from race one saw Gordon Shedden third, with the Honda man moving ahead of team-mate Matt Neal in the standings as a result.
Behind them, Paul O'Neill battled ahead of Aron Smith's Ford with a robust move at the hairpin to take fourth and the best result to date for the Speedworks team, with Nick Foster and Smith rounding out the top six.
Points leader Neal could only take eighth after being forced to run wide at Clark's on the penultimate lap after contact from Andy Jordan, while Jason Plato was plagued by a suspected engine issue and could only trail in eleventh.