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In This Issue:

• Readers Challenge: Low Oil Pressure

• Book Bits: Water Spells Trouble for Bearings

• Today's Tip: Recurring Water Contamination Problems

• Q & A: Switch to Synthetics?

Readers Challenge

Low Oil Pressure

Imagine a small construction company in Minneapolis, MN USA. One winter morning you attempt to start the engine of a dozer that has been sitting outside for several days. Since last running the engine, outside temperatures have slowly dropped to a temperature near -25°C (-13°F).

The dozer's motor oil viscosity is SAE 10W-30. The engine cranks slowly but still starts. However, the oil pressure is very low and stays low. What might have caused this? What risks or damage to the engine can result? What is the solution to the problem? What lubricant physical properties tests might have revealed this problem? What contaminants in diesel crankcase oil can compound the problem?

Submit your answer at http://www.noria.com/challenge.asp before Monday, February 10, 2003. Lube-Tips editors will choose the best answer and the $50 recipient will be announced next week.

CONGRATULATIONS to Nate Long, project specialist, Haas TCM Corporation - the winner of last week's Readers Challenge. See the winning response, as well as other responses at: http://www.lube-tips.com/challenge/

Book Bits

Water Spells Trouble for Bearings

From "Machinery Failure Analysis and Troubleshooting"

For corrosion to occur, water must be present. Free water, in particular, will settle on machinery surfaces and will displace any protective surface oil film, finally corroding the surface. Emulsified water and dissolved water may vaporize due to frictional heat generated as the lube oil passes through bearings. Very often, though, the water vapors recondense in colder pockets of the lube-oil system. Once recondensed, the free water continues to work away at rusting or corroding the system.

More information about the book "Machinery Failure Analysis and Troubleshooting"

Today's Tip

• Large hydraulic reservoirs operating outdoors often develop a problem with recurring water contamination. The problem often is related to the humidity in the air. When hydraulic systems operate, the oil heats up and expands. If the system is shut down at night, the oil will contract and fresh humid air from the outdoors will enter the reservoir through the breather.

  By morning, when the outside air temperature has cooled significantly, the humidity introduced into the reservoir usually has condensed into water droplets in the oil. To correct and avoid this, use water removal filtration offline to remove any free and dissolved water and add a desiccant type breather to filter moisture out of any air entering the reservoir. (Submitted by Brian Groff, Maintenance Supervisor, Cargill Salt)
  

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Q & A

Switch to Synthetics?

"I am considering replacing the mineral oil in my engine with a synthetic oil. The engine has 50,000 miles on it. I have heard that the mineral oil and synthetic oil are compatible. Is this true?"

Generally, the reference to synthetic oil for an engine, means a lubricant is formulated with a polyalphaolefin (PAO) base oil. PAO, which is often called synthesized hydrocarbon, is pure and is compatible with mineral base oils.

However, because the PAO base oil does not dissolve additives effectively, it is usually formulated with an ester co-base (usually di-ester and/or polyol ester). The additives are soluble with the ester and the ester is soluble with the PAO.

Likewise, the PAO tends to cause seal shrinkage and the ester causes seal swelling, so the effects are offset when both base oils are present. It is the ester that can cause problems when one changes from mineral to synthetic. Ester base oil used alongside PAO base oil in lubricant formulation has excellent natural detergency. In other words, it will clean up varnish on component surfaces as a result of thermal and oxidative degradation of the lubricant. When one switches from a typical mineral-based engine oil to a typical synthetic-based oil, the varnish layer will be removed by the ester in the synthetic oil and become suspended.

This suspended material can rapidly clog filters and can block oil flow passageways and lead to component starvation. The same is true for gearboxes and other industrial machines. So think twice about switching to synthetic oils in applications where the engine or other machine has been operating for some time with mineral oils. If you decide to make the switch, try to clean the system before making the change, then monitor it carefully once you start it up.

Drew Troyer, Noria Corporation

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