SEAL AS 8C5157 - Caterpillar

Introduction
Caterpillar engines that are operated at high altitudes are severe duty. In order to optimize engine life, adjusting engine oil maintenance schedules and using a high quality oil is recommended. High altitude operation may increase the soot level in the engine oil. Increased levels of soot can cause oil deterioration, deposit formation, and abnormal wear. More frequent oil drains and premium performance lubricants can offset these negative factors.Altitude
The air at a high altitude is less dense than the air at sea level. The air contains less oxygen at a high altitude. All diesel engines require oxygen for the efficient combustion of diesel fuel. Diesel engines that are operating at a high altitude may experience the following conditions:
Increased exhaust smoke
Reduced power
Increased soot levels in the oil
Higher exhaust temperatures
Higher turbocharger speedsCompensating for Higher Altitudes
A turbocharged diesel engine can compensate for low air density until the engine reaches the exhaust temperature limit or the turbocharger speed limit. Excessive exhaust temperature could result in the following conditions:
Increased heat load on cooling system
Reduced engine oil life
Reduced oil film thickness
Increased component wearCaterpillar diesel engines are protected from excessive exhaust temperature and excessive turbocharger speed. The engine restricts the maximum fuel rate at higher altitudes. The altitude capability of an engine is defined as the maximum altitude an engine can be operated at rated power and rated speed without violating the maximum allowable exhaust temperature and turbo speed.Caterpillar Definition of Altitude
The Caterpillar definition of high altitude varies by the type of engine and family of machine. Some of the Operation and Maintenance Manuals (OMM) use altitude to define normal and safe operating conditions for the engine oil. At altitudes below 1830 m (6000 ft), a 500 hour oil drain is permitted. For engines that operate above 1830 m (6000 ft), the oil drain schedule is every 250 hours. An oil sampling and oil analysis program is required to extend engine oil drains beyond 250 hours.Effects on Engine Oil at High Altitudes
There are two concerns for the engine oil at high altitudes. The first concern is increased soot loading. The second concern is increased oxidation.First, engines that are operated at a high altitude are under severe operation. When you operate at severe conditions, it is beneficial to select premium maintenance products for the engine. The following premium maintenance products are recommended when you are operating the engine in severe conditions:
Engine oil
Engine oil filters
Fuel filtersPremium engine oil contains special additives that are designed to limit harmful wear that is caused by soot. The premium engine oils also contain additional anti-oxidants that limit thickening of the oil and wear. This is caused by oxidation of the oil.The engine should be placed on an oil change program. A oil change program evaluates all of the factors of oil life and engine life. An optimized oil change program will provide a service interval that reduces the harmful aspects of soot at high altitude and increased oxidation.Selecting Premium Engine Oil
Engine oil with a high API category rating is the best