Mooney took Dennis Black (82v) to the wall early in the Grand Slam, but Black waited and as the field exited turn four on the last lap, squeezed Mooney against the wall allowing Matthews to steal the race by less than one 10th of a second.
It was a good weekend for Mooney - on Saturday night he had raced at Palmerston North and for the second season running finished third in the Manawatu Stockcar Champs.
Mooney has enjoyed a number of podium finishes this season in big events, and will be one of the favourites for the West Coast Stockcars in April.
Wins in the Adult Ministocks were shared between Jesse Black (82V), Brandon Jurgeleit (48P) and Ayrton Smith (64V).
Black took the win in the first race, forcing Smith wide on the final corner and prompting a massive fist-pump as Black took the chequered flag.
The Youth Ministocks provided more fast, clean racing.
Visitor Cameron Swift took the opening race in 48B, then Dylan Smith (53V) made a late pass to win the second race.
Smith was off pole in the feature race, and showed the field a clean pair of heels.
A good field of sidecars enjoyed the track conditions.
Craig Scott and Bryce Rose (62V) took the first and third races.
The combination almost had a hat-trick when Scott tried to put a move on Aaron Rose and Amelia Stanley on the final corner of the second race.
Scott backed off for a moment to avoid hitting Stanley, and the 34V combo held on for the win.
The Production Saloons again provided close racing, and although John Caird (53V) had two wins, he had to work hard for them.
John Huijs (74v) ran away with the second race from the front of the grid, whilst Jason Pointon (71V) had to be content with three second placings.
There's no racing at Oceanview over Easter, but the next meeting will more than make up for that.
The West Coast Superstocks, West Coast Stockcars and West Coast Streetstocks titles will all be decided.
There will also be three Superstock Memorial races.
In addition, the Heiby Memorial Youth Ministocks will attract a capacity field of 50 cars.
Racing will take place on the evening of April 2 and then the following afternoon.