4. DPF’s Limit Lube Ash Ash Volatility Phosphorus Sulfur CJ-4 2007 API CI-4 2002 1.5-1.3% Range CDPF No After-Treatment 1.0% Range
5. Engine Durability Tests for CJ-4 Oil Demand Increased Performance Caterpillar C-13 Oil Consumption Blow-By and Piston Deposits Cummins ISB Slider Valve Train Wear and After-Treatment Mack T-12 Power Cylinder Wear and Oxidation Cummins ISM Power Cylinder, Valve Train Wear, Filter Life and Sludge Control
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Editor's Notes
Each time the EPA introduced a new emissions level, the new engine hardware required an higher performance from the oil, and new, more expensive engine tests were added.
As performance levels went up, more additives were added to the oils. With the addition of exhaust aftertreatment (Diesel Particulate Filters) the ash content of the lube was seen to plug the filters. For the first time, a new oil category has chemical and physical limits in addition to engine performance limits.
Limits are placed on Ash, Sulfur, and Phosphorus to protect traps from plugging and catalyst poisoning. Volatility limits help control consumption.
The API CJ-4 Engine Test and Performance Criteria which are a variety of tests that are run with engine oils to make sure that engine oils will work well. OEM’s identify performance needs and develop special tests to stress the oil in that way. The key tests are shown here, although there are several more. Each engine oil that puts an API sticker on their label goes through the whole battery of tests in order to license the API symbol on their product. This full round of tests for conventional oil costs over $1.5 million dollars.
Some tests had shown that Biodiesel when partially burned in a combustion chamber could generate extra fatty acids which get into the lube oil. The Engine Manufacturers Association determined the three different runs that would be most advantageous to determine the impact of a different fuel on the engine, and those were selected to be the Cummins ISB engine, which focuses on valve-train wear, the Caterpillar C13 engine, which focuses on oil consumption and iron piston deposits, and the Mack T-12, which covers liner wear, ring wear, bearing corrosion, oxidation, oil consumption and gives some information on soot viscosity increase and on load temperature pumping at high soot levels.
The National Biodiesel Board cooperated with engine manufacturers association to sponsor a testing program that cost around $400,000, to determine if there were any effects on the lubricant performance if B20 was used as the fuel instead of conventional diesel fuel. The plan was to take the standard engine oil tests that are used to qualify engine oils and run those tests with B20, using the reference oils, and then compare the lube performance of those performance with what would be expected with No. 2 diesel. So the fuel was a B20 blended from a particular type of fuel that had known performance, and a B100 meeting D6751.
So how did these tests come out? We don’t have time in our short period today to go over all the in depth results, but by way of summary, the control parameters in each one of these endurance tests, which were designed to stress the engine and the engine oil as much as possible, were examined. The examination showed that all wear data were within acceptable limits, all control piston and ring deposits were within acceptable limits, and a really good overall performance of the engine oil with B20 in all three of these type of tests. The only issues that we saw were with lead corrosion and T 12 oxidation, which were slightly worse in the Mack T-12 than what we’d expect to see with diesel fuel. The lead corrosion apparently results because the fatty acids are not as easily neutralized as mineral acids derived from fuel sulfur. The apparent oxidation likely comes from fuel dilution which in the case of B20 adds esters to the oil which are shown as “oxidation” by the InfraRed measurement method. This has not caused problems in the field, but was something we noted with the tests. Some of the engine companies are not worried by this at all, while others are still thinking it over to determine if they will recommend any changes or modifications with B20 blends. The non rated parts of the engine appeared clean and free from sludge which could be an indication that the oxidation was more of a manifestation of the test than of problems in the engine.
The bottom line here is that no special oils are needed. Both Oil companies and OEM’s recommend starting out with a conservative drain interval when switching to a B-20 fuel. The “severe duty” drain recommendation is a good place to start. Then trend your used oil analysis with special attention to TAN and TBN as well as wear metals (keeping an eye on used oil lead.) Set the drain interval for your duty cycle at a place where the TAN stays below the TBN and where the Pb is low.
