Maintenance 93 Checking Oil Level Note: DO NOT let the oil level fall below the lower marking on the dipstick. DO NOT overfill so the level is above the upper marking on the dipstick. Wait five minutes after shutting off the engine before checking the oil level. This gives the oil time to drain back to the oil pan. Crankcase Air Breather CAUTION If the Crankcase Breather tube is not maintained on a regular basis, it will become plugged. When plugged, excessive crankcase pressure buildup may cause crankshaft seal leakage. Check and clean the crankcase ventilation system at every annual service.