Do you have engine oil? The level is low.
'Olio' — 'O-lyo'. Two syllables; 'io' is a diphthong.
Ask at the station shop when your car's oil warning light comes on or when you check the dipstick and find the level is below the minimum.
'Dell'olio' uses the partitive article 'dell'' (some oil). 'Motore' clarifies it is engine oil. 'Il livello è basso' means 'the level is low'. Most Italian petrol station shops sell standard engine oils.
Che tipo di olio serve a questa macchina?
What type of oil does this car need?
Asks for guidance on the correct viscosity.
Dove si controlla l'olio?
Where do you check the oil?
For complete beginners — asks where the dipstick is.
Mette lei l'olio o lo faccio io?
Do you put in the oil or shall I do it?
Checks if the attendant will help with the top-up.
Italian petrol stations typically stock basic engine oils, coolant, and screen wash. For specialist oils, a car parts shop ('ricambista auto') is better equipped. Many Italian mechanics are generous with quick advice for free.