Diamond DA 40 Flight Manual page 205

DA 40 AFM
6.4.3 CALCULATION OF LOADING CONDITION
For airplanes equipped with the optional Long Range Tank,
a restricted range of permitted CG positions applies.
For the mass (weight) of the fuel, a density of 0.72 kg/liter
(6.01 lb/US gal) is assumed. For the mass (weight) of the
engine oil, a density of 0.89 kg/liter (1.86 lb/US qt,
0.84 kg/US qt) is assumed.
In the following example it is assumed that the fuel tank is
not full at take-off.
Doc. # 6.01.01-E
CAUTION
NOTE
NOTE
Rev. 8 01-Dec-2010
Mass & Balance
Page 6 - 11