RING-RETAINING 3904157 - Caterpillar

What is the difference?
1. The API "CD" category is a very broad classification. This means that there can be a wide variation in the performance level from one API CD or CE oil to another. The API CF-4 oil category requires more performance tests, to higher and stricter standards. This means API CF-4 oils have a narrower performance band within the API CF-4 range than API CD oils do. API CF-4 oils also have a higher average performance rating than API CD or CE oils.2. The API CF-4 oil qualification test includes new tests, such as the Caterpillar 1K single cylinder engine oil performance test. This test defines a much higher oil performance level than the old API CD class (which was based on Caterpillar's 1G2 test developed in 1955). The API CF-4 oil qualification tests use the high top ring piston design that has reduced the top ring crevice volume.3. API CF-4 oil also has a significantly higher piston deposit threshold temperature capability compared to API CD oil. This means that the API CF-4 oil can withstand higher temperatures before coking and becoming "cooked" into hard carbon on the piston crownland and in the ring grooves. API CF-4 oils, on average, have 60°C higher temperature capability than an average CD oil.4. API CF-4 oil, by design and additive package formulation, has greater dispersing capabilities. This dispersancy additive package controls buildup of soot particle size in the oil by keeping soot particles dispersed more evenly. Poor soot dispersancy can lead to plugged oil filters, reduced oil change intervals, or an increase in ring and liner wear, resulting in reduced overhaul life.5. Because of the oil consumption limit required to pass the API CF-4 qualifications most, if not all, API CF-4 oils are multi-viscosity oils. Engine oil qualification tests have proven that multi-viscosity oils have better oil control and minimize oil consumption.In summary, API CF-4 oils have higher temperature capabilities, greater soot dispersancy capability, must pass additional tests at higher levels of performance, have a narrower performance band and are usually multi-viscosity. All of these factors result in a much better engine lubricant, leading to reduced oil related problems and/or longer engine life.
Caterpillar Recommendations
Since early 1992, API service category CF-4 oils have been and are the current recommendation for all 3500 diesel engines. This is the only way of assuring that the engine will provide optimum life to overhaul, as well as achieving the performance requirements. Providing one API recommendation also helps keep the recommendation as simple as possible.
However, if 3500 Phase 0 or Phase I engines are currently running on other than API CF-4 oil "successfully," these engines can, most probably, continue to use this oil. It should be recognized that "running successfully" on non - API CF-4 oil may mean that optimum engine overhaul life has not been achieved. Also, if the engine load factor or the oil formulation significantly changes, this may warrant having to change to API CF-4 oil.
If articulated (two piece) pistons are used