The Oil&Water vs Oil&Oil vaccines option is only available when using a Dual configuration and relevant only when using a Dual Injection Head and NOT the Twin Injection Head.
The water-based vaccine MUST be in the Secondary Unit.
Turn on the pHi-Tech device.
2. Navigate to the Mode icon and press ok to enter the screen
3. Press OK to enter the 'Vacc.Mode' field.
4. Press the down button to see the 'Oil&Wat' option.
5. Press OK.
6. Navigate down to the Esc filed and press ok.
The article explains how to change from Oil&Oil to Oil&Water mode.
If you need the opposite, follow the instructions, and replace the Oil&Water with Oil&Oil.