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Entry type: FAQ Entry ID: 109755312, Entry date: 01/29/2018

SIMOGEAR, 2KJ1/2KJ3: Quick test to evaluate the condition of oil

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How is the oil condition evaluated
In addition to having the oil analyzed in an appropriate institute, you can carry out a quick test yourself at a favorable price. The results are quickly available – however, a certain amount of experience is required in interpreting them.


Fill the specimen of oil in a test tube or similar container, and allow it to settle for approximately 30 minutes.

Then evaluate its appearance:

 AppearancePhotograph Recommendation 
 Clear, transparent 

 The oil can be reused
 Black, opaque 


Change the oil and have a laboratory analyze it

  • Always change the oil if only a small amount is involved (an analysis is not cost-efficient)
  • If larger amounts of oil or damage are involved – or the causes are unclear – then always have a laboratory analyze the oil
 Cloudy, milky 


Cloudiness or a flocculent appearance indicates water and / or liquid contaminants. Special polyglycols are in some instances hygroscopic  and absorb water. This water that is absorbed results in a milky cloudiness.

A dark or black color indicates residue, serious thermal decomposition (check the smell) or contamination.

Different densities of various products can cause the formation several phases in the test tube. A combination of mineral oil or PAT oil and polyglycol is an example. As soon as both base oils are filled in a test tube, then typically different phases quickly form. This does not happen when mixing base mineral oils as the specific density is approximately the same. Water in mineral oil or PAO oil drops to the bottom with the oil floating on top.


Assessing the water content

With the crackling test, a small amount of oil is heated up in a test tube or on a piece of aluminum foil using an open flame. The water is vaporized along with the associated typical crackling noises. This cracking test can be carried out for all oil types.

 Water content
(approximate data)
 Appearance ObservanceAssessment 
75 … 100 ppmSlightly cloudyLoud crackling sound, cloudiness disappearsInsignificant, the oil can be reused
100 … 400 ppmSlightly milkyBriefly foams up, cloudiness disappears

As above, however the ability for

the air to be separated out is already poorer
Approx. 1000 ppm (approx. 0.1%)Completely milkyFoams up a lot, slight amount of steam/water vapor

Poor air separation capability, risk of foaming and  corrosion, change the oil

Above 10,000 ppm  (>1%)Completely milky, yellow tinge, partially free waterFoams up a lot and for a long time, lots of steam/water vaporAs above, the load capacity of the film of lubricant quickly decreases above a water content of 1%


Iron content

The iron content can be quickly assessed using a suitable bar magnet (if necessary using a telescopic extension). When dipped in the gear unit oil it attracts any iron particles.

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