Cummins/Onan GTA38 / GTA50 — Lubricating Oil and Filter - Changing
Maintenance · Lubricating system
For the Cummins/Onan GTA38 / GTA50, from the Cummins/Onan owner's manual.
Applies to: Cummins/Onan GTA38 engine, Cummins/Onan GTA50 engine
Before you start
- Avoid direct contact of hot oil with your skin.
- Pre-lube the engine or crank with manual fuel valve off until oil pressure appears.
Procedure
- Operate engine until coolant reaches 60C [140F], then shut off and remove oil drain plug.
- Clean around oil filter head; remove filter with 1 1/8 to 1 3/16 in wrench.
- Make sure correct full-flow filter is installed (1 1/2-16 in threads).
- Fill new filter with clean lubricating oil.
- Coat gasket sealing surface with a light film of oil.
- Install filter as specified by the filter manufacturer.
- Install oil drain plug; torque 100 Nm [75 ft-lb].
- Fill engine to proper level with recommended oil.
- Operate at idle and inspect for leaks.
- Stop engine, wait 5 minutes, check level and add to H mark.
Tools required
- Oil filter wrench 1 1/8-1 3/16 in Amazon
- 1 1/4 in wrench or socket Amazon
- Pipe cutter or hacksaw Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Oil drain plug 100 Nm [75 ft-lb]
- Pan capacity GTA38 FridayParts $14.33 140 L / GTA50 FridayParts $316.79 204 L
Source: Cummins/Onan owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.