Automobile Deduction for Volunteer Service

[bhelin]

According to the IRS, I can take either $0.14 per mile, or actual cost (gas and oil) for volunteer miles driven by automobile.  For my 2018 taxes, TurboTax appears to only allow the $0.14 per mile when entering my data.  How do I enter the actual cost for gas and oil?

[Critter]

It is entered as a CASH donation ... do NOT use the mileage section. 

[bhelin]

Thank you.