Generator Maintenance Service for the generator set is much like the service you perform on your automobile. The generator set should have oil and all filters changed on a regular basis  The generator should be kept free from dust and occasionally connections should be checked for looseness. These procedures are normally done every 100 hours  or 3 months whatever comes first as suggested by our maintenance schedules. Severe weather patterns can increase the maintenance requirements, i.e., excessive dust, heat, moisture. Also any commercial type use or prolonged usage. The unit should also be checked from an electrical standpoint to be sure that it is performing as it was designed. Oil Changes Oil Dip Stick Engine oil has limited life - after a certain point it starts losing lubricating qualities and carbonizes. Once it happens, the engine gets contaminated with carbon deposits or sludge that significantly shorten engine's life. When you change oil at or before manufacturer suggested interval, you change the oil before this "carbonizing" point, engine remains clean and once refilled with new oil ready to work hard again. If the engine oil has not been changed for long, carbon deposits start clogging the oil pickup screen decreasing oil supply and increasing friction.  Compression decreases and engine start wearing much faster. If you don't remember when you changed the oil last time - just check the oil on the dipstick. And every time you change the oil, the oil filter should be and and or replaced as well. On your gas or diesel generator you are required to change change your oil after the first 25 hours and then every 100 hours or sooner. The cost of the oil is far cheaper then the cost of a new engine. This is an area where you have great control over how long our generator will last it really does not take long and makes a huge difference in the life of your engine. Silent Diesel Generator Open Frame Diesel Generator After the initial break in period we recommend switching to synthetic oil.  Synthetic oil can withstand higher temperature and can work longer without losing its lubricating qualities. It doesn't get thicker at below-zero temperatures providing good engine lubrication at a cold start. After your generators first oil change and initial break in period a good quality synthetic oil designed for diesel engines is recommended.  Mobil1 is one of the best ones you can get however make sure what you buy is specifically for a diesel engine, there is a difference. Procedure: Place a pan under engine near the drain plug. (Silent Diesel Generators the oil will spill on the bottom of the frame and out of the trench below it) Remove the oil filter and wash with soap and water, let dry while oil drains. Washable Oil Filter from our diesel generators. Replace oil filter and oil drain plug and refill with synthetic 15w40 diesel oil to level shown.   Valve Adjustment Adjustment of the intake and exhaust valve head clearance governs the performance of the engine, and must be performed accurately. The intake and exhaust valve head clearance must always be checked and readjusted, as required, when the engine is disassembled and reassembled, and after every 200 hours of operation. Your first valve adjustment should be at 50 hours. Adjust the valve head clearance as described below. Adjustment [valve lash] Make this adjustment when the engine is cold. (1) Remove the valve rocker arm cover. Careful not to damage the gasket under it. (2) Crank the engine and set the piston to top dead center (TDC) on the compression stroke. [when both the intake and exhaust valve rocker arms are "loose" it is the compression stroke.] (3) Check and adjust the intake and exhaust valve head clearance of the piston. Loosen the lock nut and insert the feeler gauge, adjust the "valve adjustment screw" until the you feel a slight drag on the feeler gauge. Set Gap Between Valve Spring and Rocker Arm The idea is to measure the gap accurately, if it is too loose or if the feeler is squeezed too tight, forcing the valve to open slightly against the force of the valve spring, the reading will not be accurate. With the feeler in place, hold the screw adjuster in place while tightening the jam nut. Recheck the clearance to make sure it did not move when tightening the jam nut. Adjusting without a feeler gauge Set the head clearance to zero by tightening the adjusting screw, being careful not to tighten the screw too tight. Then adjust the valve clearance to the maintenance standard by backing off the adjusting screw by 1/3 of a turn, tighten the lock nut. Example Of Rocker Cover Gasket - Use caution when removing cover as to not damage this gasket. If you require a new one please contact our parts department.