How antiwear additives work

Inspect the vent hole in column-type vented level gages routinely. In dirty environments, the vent hole can become easily plugged, causing an air lock in the gage headspace. This will result in a false oil level (higher than reality) in the gage. Many prefer dual-port gages instead (unvented).

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From "Lubricant Additives"

To be effective, antiwear (AW) additives form protective films by chemical or physical reaction with the surface. They minimize the removal of metal through formation of lower shear-strength films that reduce friction, by decreasing the contact temperatures or by increasing the contact surface reducing the effective load. The most effective additives contain sulfur or phosphorus, or both, that reacts with ferrous metals.

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Lube-Trivia: Which VI is Best?

Test your knowledge and prepare for ICML lubrication and oil analysis certification with Lube-Trivia.

QUESTION: Which mineral oil has the higher natural viscosity index, paraffinic or naphthenic?

Q & A: Using Viscosity as a Drain Indicator

"My laboratory provides feedback on kinematic viscosity at 100 degrees C for our engine lubes. At what level of viscosity change should we drain the engine oil?"

Because a change in viscosity, whether an increase or decrease (or both, therefore negating any perceivable change), can be an indicator of a number of problems, monitoring viscosity alone as an indicator of engine oil change is insufficient, especially on engines.

Engines can suffer fuel dilution resulting in a decrease in viscosity, as well as glycol or soot loading resulting in an increase in viscosity. Changing the oil will not cure the root cause of these problems. In addition, if a multigrade engine oil is used, then a decrease in viscosity is possible because the viscosity index improvers shear during service. Further inspection or a more detailed confirmation analysis will be necessary to determine the cause if the viscosity changes before the end of the anticipated service life.

However, on engines, setting both upper and lower caution and critical limits will be an alert to oil life and contamination issues. The recommended lower limits are -5 percent and -10 percent, while the upper limits are +10 percent and +20 percent. These kinematic values are based on changes in cSt at 100 degrees C.

Martin Williamson, Senior Technical Consultant, Noria UK

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