Cummins ISB 275 Diesel Engine Oil Change Procedure
After warming up the engine to normal operating temp:
Submitted by Herb Petersen.
- Remove Drain Plug, 11/16" wrench, over drain container that holds at least 5 gallons.
- Remove Oil Filter.
- Take new filter, Fleetguard # LF 3729 and pour one quart of 15 W 40 Oil, Spec.  CF/SG or better, into the filter.   Apply a coat of oil to the O-ring.
- Spin on oil filter until it makes contact with base.   Tighten an additional 3/4 turn.
- Replace Drain Plug, 11/16" wrench, do not over tighten.
- Lift up bed, open up engine access cover and block open.
- Add 15 quarts 15 W 40 Oil, Spec.  CF/SG or better.   Use funnel (optional) in oil fill hole located on rear of valve cover.
- Replace filler cap.
- Start engine and let idle until oil pressure comes up and stabilizes.   Turn off engine.   (Note: You must get oil pressure on the gauge on the dashboard within 15 seconds.)
- Check oil dipstick for level.   (NOTE) Not all dip sticks are calibrated properly, the reading on your dip stick now indicates a full crankcase.
- Put engine cover back down and lower bed to former position.
- Dispose of oil and oil filter properly.
LP Generator Oil Change Tip
Since the oil filter is recessed into the generator cover, most oil filter removal tools cannot get a good grip to remove the filter.   Go to WalMart and get a cup-style oil filter wrench - the kind for a Mercedes or Audi.   This will fit and make removal of the filter easy.   Note - Onan sells a replacement filter with a socket on the end that will fit a 3/8" drive.
Submitted by Bob Cook.