When checking the oil level in a centrifugal pump, it is a good practice to have a sightglass on both sides of the pump. If the pump is not installed centered in the casing, the oil level will not read correctly in the sight glass. It may read low on one side and high on the other. An average of the two readings will give an estimated oil level. (Randy Riddell, International Paper)

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To answer this question, we must take a critical look not just at the benefits of synthetic lubricants, but also the potential pitfalls. For example, synthetic lubricants are typically made by taking small building-block molecules and joining them together, a process referred to as polymerization.

Because of the amount of work required to convert these starting ingredients into finished base oils, synthetic oils are generally more expensive than conventional mineral oils, from three to five times more for common synthetics such as polyalphaolefins (PAO) to several hundred times for highly specialized fluids such as fluorinated polymers that are used in applications requiring inherent chemical inertness.

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Question: What are the consequences of a loss of dispersancy?

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"What are the possible sources of silicon in oil?"

Silicon is measured by oil analysis labs to determine dirt
ingression. While more often than not, high silicon readings
indicate dirt, there are several other possible sources. The
four most common are:

1. Defoamant additive – many oils contain defoamants based on
polymeric methyl silicone because silicone contains the
element silicon, the presence of this kind of additive will
show a positive silicon reading in spectrometric analysis.
The typical levels of Si seen under these conditions are
around 1-10 ppm.

2. Silicone-based sealant – Many sealants used for industrial
and mobile applications are silicone-based. The level of
silicon observed will of course be directly related to the
amount of sealant leaching into the lube system.

3. Casting sand – Some components are made by casting in sand (silicon oxide). Although new components are cleaned
thoroughly prior to installation, it is not uncommon to see
50-100 ppm of silicon from new equipment. This level should
drop as the component breaks-in and regular oil changes take
place.

4. Coolant contamination – Many engine coolants contain
inhibitors which contain silicon. In an engine application,
high Si readings in conjunction with other elements such as
Na, K and B may indicate a coolant leak.

Without other evidence differentiating between additives,
silicone and casting material as the source of silicon is
difficult. However, dirt ingression can be determined by
tracking both silicon and aluminum. For most common dirt, which
contains the minerals silica and alumina, tracking Si and Al,
which should show up in lock step trend in the ratio 3.4:1, can
be used to confirm dirt ingression.

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