An engine-pressurized prestart oiler for an engine having pressure lubrication is provided, which rapidly lubricates critical engine bearing surfaces prior to the starting sequence. An accumulator for storing oil and pressurized air contains an air-oil separation float, which essentially fills the internal cross-sectional area and prevents absorption of the air. Discharge and recharge of the accumulator is preferably implemented by a normally closed solenoid valve. Discharge is controlled either manually by a switch or automatically by circuitry containing ignition-off time and accumulator pressure comparators, a starter interrupter, and a prestart oiling timer. Recharge is automatic, as the solenoid valve allows oil flow whenever the engine oil pressure sufficiently exceeds the accumulator pressure. A conduit connects the accumulator, solenoid valve, and engine, connecting to the engine either at the oil pressure sensor port or through an adaptor installed between the oil filter and the oil filter mount.