Caterpillar issued the ECF-1 engine-oil standard, which the engine maker says should be applied in addition to the American Petroleum Institute (API) CI-4 standards, to protect Cat engines from soot, wear and piston deposits. In the past, Cat has recommended owners of 3500 Series and smaller engines use diesel engine oils that meet the most current specifications of the American Petroleum Institute. CI-4 oils were introduced to address the introduction of truck engines with exhaust-gas recirculation and Cat is now recommending additional performance tests to ensure the durability and reliability of all Caterpillar engines, none of which use EGR to meet emissions limits.
Part of the battery of tests necessary for an oil to achieve API's CI-4 designation are the Cat 1K or 1N tests for deposit control on aluminum pistons. Engines with articulated steel pistons are subjected to the Cat 1R test. Performance parameters in the 1R test reflect the conditions in an engine that meets current on-highway emissions limits using EGR.
Because more acidic exhaust gases pass through the combustion chamber and into the crankcase of EGR engines, oils must be able to neutralize more acid. Additives typically used to raise the oil's base number also increase the level of sulphated ash.
"As oils move up into the 1.5 percent and higher percent-ash range, they move into an area where the North American diesel industry hasn't really operated," says Mike Quinn, of Caterpillar's fluids group. "We added the 1P tests with our ECF-1 oil requirements to improve the statistical confidence level in an area where we haven't had a lot of experience."
Quinn says Cat engines, because they don't use cooled EGR, typically produce much less soot, so they don't require high-ash oils.
"There is a correlation between ash and piston deposits," Quinn says. "Higher ash levels don't always end in a problem, but if the oil is not balanced properly it could."
Cat's ECF-1 recommendation combines the qualifications outlined in API CH-4 or CI-4 performance categories with a passing grade on the Caterpillar's 1P test—a test that was included in the CH-4 category, but removed from today's CI-4 standard.
The objective of the Cat 1P test is to evaluate crankcase-oil performance in protecting against piston deposits, ring sticking, piston, ring and liner scuffing, as well as oil consumption. The test engine uses a two-piece piston with steel top and aluminum skirt. High-speed turbocharged, heavy-duty diesel engine service prior to 2002 is simulated.
The ECF-1 specification limits oils to 1.5 percent or less sulfated-ash content. Caterpillar says the ideal oils have 1.3 percent sulfated ash or less. Those oils still must pass one Cat 1P test. Oils between 1.3 percent and 1.5 percent ash must pass two Caterpillar 1P tests to satisfy the ECF-1 requirements.
Many engine oils are already claiming ECF-1 compatibility, but because Cat isn't actually testing oils or monitoring these claims it's hard to find a comprehensive list of ECF-1 qualifiers. Construction Equipment has compiled the accompanying list of vendors who are actively marketing their ECF-1 performance. Quinn suggests that the heavy-duty lubricants industry is too small for any marketers to risk sullying their reputations by making false claims.
Now that Caterpillar's ACERT engines are available for performance testing, it seems likely that API will change the CI-4 testing regimen if it is warranted. Until then, Caterpillar recommends that its customers seek crankcase oils with the ECF-1 designation.