If you're travelling around Samoa with a rental car or scooter, always plan ahead and fill up your vehicle before leaving a main town.
Upolu has several fuel stations in and around Apia and near Faleolo International Airport. There are very few outlets on the south coast of the island.
On Savai’i, fuel is available at Salelologa, Lalomalava, Maota, Saleaula, and Asau. On Sunday, fuel is available at Saleaula until 4pm, and at Lalomalava from 7am-8am (one hour).
Most stations are open from 7am to about 6pm, except Sundays. Fuel stations have forecourt attendants who do all the filling - just estimate how much you want them to fill your vehicle with, and remember to have cash on hand to pay for your fuel.