The 1983 Castrol 400 was an endurance race for Touring Cars complying with CAMS Group C regulations. The event was staged at the Sandown Park circuit in Victoria, Australia on 11 September 1983 over 129 laps of the 3.1 km circuit, totalling 399.9 km. The event was Round 3 of the 1983 Australian Endurance Championship and Round 3 of the 1983 Australian Endurance Championship for Makes.
| Position | Drivers | No. | Car | Entrant | Class | Laps |
| 1 | Allan Moffat | 43 | Mazda RX-7 | Peter Stuyvesant International | Over 3000cc | 129 |
| 2 | Jim Richards | 31 | BMW 635CSi | JPS Team BMW | Over 3000cc | 129 |
| 3 | Warren Cullen, Ron Harrop | 22 | Holden VH Commodore | Cullen Automotive Industries | Over 3000cc | 127 |
| 4 | Murray Carter | 18 | Mazda RX-7 | Valentine Greetings | Over 3000cc | 126 |
| 5 | Terry Shiel | 37 | Mazda RX-7 | Eurocars (Northside) | Over 3000cc | 123 |
| 6 | Gregg Hansford, Gary Waldon | 42 | Mazda RX-7 | Peter Stuyvesant International | Over 3000cc | 122 |
| 7 | Johnnie Walker, Gene Cook | 32 | Mazda RX-7 | Johnnie Walker | Over 3000cc | 120 |
| 8 | Scott Taylor, Kevin Kennedy | 24 | Holden VH Commodore | Scotty Taylor Holden | Over 3000cc | 119 |
| 9 | Lawrie Nelson | 59 | Ford Capri V6 | Capri Components | Up to 3000cc | 119 |
| 10 | Barry Jones, Peter Dane | 41 | Mazda RX-7 | BF Goodrich Australia Ltd | Over 3000cc | 119 |
| 11 | Jim Myhill | Mazda RX-7 | Up to 3000cc | 114 | ||
| 12 | Terry Ryan, Graham Storah | Mazda RX-7 | Over 3000cc | 113 | ||
| 13 | Ray Cutchie, Mike Quinn | Ford Escort | Up to 3000cc | 111 | ||
| 14 | John White | 61 | Isuzu Gemini | John White | Up to 3000cc | 108 |
| 15 | Brian Winsall, Louis Stoopman | Isuzu Gemini | Up to 3000cc | 95 | ||
| 16 | Joe Beninca, Peter Beninca | Alfa Romeo GTV | Up to 3000cc | 90 | ||
| NC | Andrew Harris, Gary Cooke | 9 | Ford XE Falcon | Andrew Harris | Over 3000cc | |
| NC | Ken Harrison | Ford Escort | Ken Harrison | Up to 3000cc | ||
| NC | John Craft, Don Smith | 56 | Ford Capri V6 | Up to 3000cc | ||
| DNF | Allan Grice, Colin Bond | 6 | Holden VH Commodore | STP Roadways Racing | Over 3000cc | |
| DNF | Andrew Manson, Geoff Manson | Holden VH Commodore | Roger Manson Holden | Over 3000cc | ||
| DNF | Christine Gibson | 60 | Nissan Pulsar EXA | Nissan Motorsport Australia | Up to 3000cc | |
| DNF | David Parsons, Peter Janson | 3 | Holden VH Commodore | Cadbury Schweppes Pty Ltd | Over 3000cc | |
| DNF | Dick Johnson | 17 | Ford XE Falcon | Dick Johnson Racing | Over 3000cc | 1 |
| DNF | Fred Gibson | 16 | Nissan Bluebird Turbo | Nissan Motorsport Australia | Over 3000cc | |
| DNF | Garry Rogers, Clive Benson-Brown | 11 | Holden VH Commodore | Soundwave Discos | Over 3000cc | |
| DNF | George Fury | 15 | Nissan Bluebird Turbo | Nissan Motorsport Australia | Over 3000cc | |
| DNF | Jim Fanenco, Tony Hubbard | Ford XE Falcon | Over 3000cc | |||
| DNF | Jim Keogh, Leo Leonard | 12 | Holden VH Commodore | Team Toshiba | Over 3000cc | |
| DNF | Mike Imrie, Graeme Treasure | Ford XE Falcon | CDT Performance Vehicles | Over 3000cc | ||
| DNF | Peter Brock | 05 | Holden VH Commodore | Marlboro Holden Dealer Team | Over 3000cc | |
| DNF | Peter McLeod | 50 | Mazda RX-7 | Petrolon Slick 50 | Over 3000cc | |
| DNF | Ron Dickson, Bob Stevens | 21 | Mazda RX-7 | Over 3000cc | ||
| DNF | Rusty French, Alan Browne | 4 | Holden VH Commodore | John Sands Racing | Over 3000cc | |
| DNF | Steve Harrington | 14 | Holden VH Commodore | STP Roadways Racing | Over 3000cc | |
| DNF | Steve Masterton, Bruce Stewart | 2 | Ford XE Falcon | Masterton Homes | Over 3000cc | |
| DNF | Craig Bradtke | 62 | Toyota Celica | Up to 3000cc | ||
| DISQ | Peter Brock, John Harvey | 25 | Holden VH Commodore | Marlboro Holden Dealer Team | Over 3000cc | 127 |
Note : There were probably more starters than have been listed above and laps completed by the non finishers are not known.
| Preceded by 1982 Castrol 400 |
Sandown 400 1983 |
Succeeded by 1985 Castrol 500 |