HomeEnginesGenerac 3.9 GN

Generac 3.9 GN Engine

The Generac 3.9 GN is a 3.9 L 6-cylinder naturally aspirated engine rated at 1800 rpm. It powers generator sets from Generac, including the 3.9GN and Home Standby - 40. It holds 4.55 L (1.2 gal) of oil and 5.6 L (1.5 gal) of coolant.

Also known as: GENERAC 3.9 GN

3.9 L
Displacement
6
Cylinders
1800 rpm
Rated speed
4.55 L
Oil capacity

Engine specifications

Oil capacity4.55 L
Coolant capacity5.6 L
Displacement3.9 L
Cylinders6
AspirationNaturally Aspirated
Rated speed1800 rpm

Maintenance schedule

ItemSpecCapacityPart #Interval
Oil filterFull flow, cartridge
OilGear4.55 qts.

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Common questions

What is the oil capacity of the Generac 3.9 GN?

The Generac 3.9 GN engine has an oil capacity of 4.55 liters.

What is the displacement of the Generac 3.9 GN?

The Generac 3.9 GN has a displacement of 3.9 liters with 6 cylinders.

Which generators use the Generac 3.9 GN engine?

The Generac 3.9 GN powers 2 generator set(s), including Generac 3.9GN, Generac Home Standby - 40.