Lubes and Biodiesel: Maladroit Bedfellows?

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HOUSTON – Biodiesel contamination can degrade performance of crankcase lubricants, though it does appear that some of this degradation can be mitigated by engine oil formulations, an Infineum USA L.P. official told the NPRA International Lubricants & Waxes meeting earlier this month. Further complicating the issue, he said, standard tests may not show the impacts.

Glen P. (Pat) Fetterman Jr., industry liaison advisor for Infineum in Linden, N.J., said the company performed bench testing to see what happens when engine oil is contaminated with biodiesel fuels. We looked at two different oil qualities in an array of tests, Fetterman said. And we tried to see if there was possibly some difference oil quality had on the impact of biodiesel.

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Top-tier oil products generally did a much better job of maintaining the viscosity control than did mid-tier when contaminated with biofuels, according to Fetterman. There does appear to be some sort of formulation-related impact on the contamination, he said.

In a corrosion test, top-tier oils showed less degradation. For both copper and lead, the addition of 10 percent ofNo. 2diesel had zero impact on the corrosion tendency of the oil, he said. But when we begin putting the biofuel in, looking at both copper and lead, we see a very dramatic increase in the corrosivity of the oil with the mid-tier product, and pretty good control with the top-tier products.

Field tests showed biofuel contamination had less impact in other areas. Our field tests showed relatively little impact on wear and maybe a directional increase in deposits, Fetterman said. The engine bearings, in spite of having dramatically elevated lead levels, are actually in very, very good condition.

He said one of the concerns with biodiesel is its significantly higher boiling point. With conventional diesel fuel, he explained, if some fuel gets loose into the engine oil sump, the generally high operating temperatures will dry the sump temperature to the point that the fuel will vaporize and be driven out of the engine. With the biodiesel, that doesnt happen, Fetterman said. It will actually accumulate in the sump.

Fetterman said some of the engine-related concerns about possible impacts of biodiesel contamination on crankcase lubricants include whether it will change sludge-forming characteristics, bearing corrosion, piston cleanliness and ring sticking. Concerns relating to used oil include oxidation – whether putting fuel into oil changes the oxidation characteristics of used oil – andhow the buildup of a different kind of wax impacts the pumpability of the used oil. There are also concerns about general viscosity losses, and the impact ofcontaminants.

Standard tests may not show the impacts, he said. If youre going to be running tests to look at the impact of biodiesel, you need to actually look at the test positions and operating parameters and make sure theyre running environments [so] that you actually get data youre looking for, said Fetterman.

He said a field test still running involves River Valley Trucking, a part of Tyson Foods. Its fleet includes 11 Mack E7 427 engines and 10 Cummins 1SX 450 engines. After 14 months and about 140,000 miles on No. 2 diesel fuel, the company switched the trucks to B20 biodiesel fuels. B20 biodiesel consists of about 20 percent bio component blended with 80 percent petroleum derived fuels.

We can look at things like soot, viscosity, base number and we can compare the baseline data, Fetterman said. There really is essentially no difference between the baseline data and the year-plus on B20.

Sludge control was slightly poorer with the biodiesel, but it did a pretty good job. No copper was exposed in bearings despite higher lead levels, he added. Piston deposits showed mixed results.

Fetterman said the National Biodiesel Board has agreed to sponsor engine tests using B20 biodiesel in the Mack T-12, Cummins ISB and Caterpillar C-13 engine sequence tests. Last year, Lubes’n’Greases magazine pegged the cost of running these three tests at roughly $300,000, plus substantial fuel surcharges.

Depending on the test conditions, you may or may not actually get any of the bio component into the used oil, he said. My fear is theyll spend a bunch of money and not generate used oil that has significant biodiesel, and come to the conclusion theres no issue here.

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