Copyright 2019 Discovery Owner's Association, Inc.

Cummins Maintenance Procedures

Cummins ISB 275 Diesel Engine Oil Change Procedure

After warming up the engine to normal operating temp:

  • 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.

Submitted by Herb Petersen

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


The DISCOVERY OWNERS ASSOCIATION, INC, was formed to promote the sharing of information and the camaraderie of fellow Discovery motorhome owners. Membership in the club is limited to owners of Fleetwood Discovery motorhomes.


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