Sterling SDF 250 - Manual (Page 39)

SDF 250/400/500
Maintenance 5-2
F
Please observe the maintenance schedule.
Before starting maintenance work, clean the equipment of oil, fuel
or lubricant.
Ensure that materials and incidentals required for operation as
well as spare parts are disposed of properly and in an
environmentally sound manner.
Use only original Sterling spare parts.
Keep record of all maintenance and repair procedures.