[Denniss]

Even if equipped with 300l drop tanks the Bf 110 had no additional oil tanks, this was only required for use with 900l drop tanks.
Daimler-Benz datasheets state4-8 g/PSh as oil usage, Dauerleistung with 950 PS and 8g/PSh would result in 8.95l oil consumption. This high 8g/PSh consumption is only assumed for max power ratings. With further rpm reduction to ~22000 for most economical cruise you'd probably end up close to the lowest rating.

DB 601A/B and 601E engine manual actually state 5-12l oil usage