Cameron Dawson banked the best lap of the day to top the free practice timesheets with a lap of 1min 41.203secs, as Kier Armstrong held off Sam Laffins to end the day second.
Behind Laffins, Aaron Silvester was fourth fastest, as Silverstone polesitter Owen Jenner finished the day fifth.
Pirelli National Junior Superstock with Santander Consumer Finance, Oulton Park combined practice:
1. Cameron Dawson (MSS Performance) 1min 41.203s
2. Kier Armstrong (Lincolnshire Racing Mulisha) +0.157s
3. Sam Laffins (Uggly & Co by Binch Pro) +0.194s
4. Aaron Silvester (A&J Racing) +0.213s
5. Owen Jenner (Jenner Racing) +0.472s