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Q & A History:

Question #: 4

Subject: Engine Oil

Date: October 1, 2024

Question: What is this new Ford specification WSS-M2C171-F1

Answer:

Ford has identified that for certain engines they require a specific combination of additive technologies in order to provide optimum protection of the metal components.  Engine oil specifications are identified to meet industry standards and you will find API (American Petroleum Institute) designations on commercial diesel engine oils and for service fill gasoline fueled vehicles. Many oils are approved for use in heavy duty diesel and gasoline fueled engines.  Recent changes to the standards to which engine oils are approved have dictated reduced levels of phosphorus in passenger car engine oils.  Ford introduced the WSS-M2C171-F1 specification to identify oils that have a higher level of phosphorus.  If your operating manual calls for oil meeting this standard you should look for oils that meet WSS-M2C171-F1. 

Question #: 3

Subject: Hydraulic Oil

Date: October 1, 2024

Question: The equipment manual specifies that the lubricant must be an ISO VG 32 hydraulic oil.  What does this mean?

Answer:

The equipment manual is specifying the recommended viscosity for a lubricant according to the International Standards Organization (ISO).  Here is a chart showing the viscosity grade (VG) ranges according to the standard.  The chart identifies the viscosity in the official units of mm2/sec but the term centiStoke (cSt) is more commonly used by lubricant suppliers in their literature.  In this example, the recommended oil viscosity should be between 28.8 and 35.2 cSt at 40°C.  You may notice that the viscosity range of each grade is +/-10% of the designated grade (eg 32 +/- 3.2) and each successive grade has a viscosity approximately 50% higher (eg 32 + 16  = 48 or approximately 46, 46 + 23 = 69 or approximately 68, and so on).

The lubricant specification is also calling for the fluid to be a hydraulic oil.  We would need more details about the application to provide more clarification on that requirement.

Question #: 2

Subject: Bearing Oil

Date: June 20, 2024

Question: How do you know when to change oils, replace or re-grease bearings?

Answer:

Good question

Surprising how many seem to get it wrong. For example, a study by the Electric Power Research Institute found that more motor bearings failed because of overgreasing rather than undergreasing. Others report that most rolling element bearings never reach their design fatigue life with the leading cause being improper lubrication.

The answer depends on the life cycle of the component. For example, if under warranty then follow the equipment manufacturers recommends. After that you can do more to optimize the maintenance. The reason being that the product you are using might be better or worse than the standard, and/or the environment, duty cycle, crafts available might be different.

Other factors to consider include importance of that equipment to safety, production, and/or the environment.   Plus, the nature of any consequential damage, the repair costs, and the risk that the repair will not be as good or better than the original.  Some equipment will justify the best efforts while others might be allowed to fail. An example of the latter might be a bathroom fan bearing. It will start to make noise and possibly seize with the motor tripping out on high amps. But even so it does not mean doing nothing, but that most such bearings cannot be relubed and bearing monitoring not likely justified. Bearings are generally not very expensive but if the shaft or bearing fit is damaged the repair costs can mount.

There are many ASTM and other tests for testing lubricants but which ones you want to monitor would be ones that best indicate adverse deterioration and/or which might be a required characteristic. This will vary depending on the equipment and the lubricant. When to change can be best determined by trending results or have a limit based on past experiences. As a rule, it is also less costly to prevent contamination then to remove it. Similarly, considering filtering or dehydrating the oil, rather than just changing it. The reason being that just putting in new oil can be many times the cost of only the oil when all the factors including purchasing, stocking, transferring, and disposal are considered.

In addition, oils are usually easier to monitor than greases but it can be done and ultrasonic have been shown to be a good tool determine when to regrease bearings and with how much grease.

In summary, it depends. There is no one answer but there can be the right answer for each application.

Question #: 1

Subject: Oil Condition Monitoring 

Date: June 6, 2024

Question: What
is available as guides to which oil condition monitoring tests to do, limits,
and when?

Answer:

Fortunately, there are a number of guides that can be used. They can be fine turned for your specification applications, history and available testing. Many commercial test labs can often compare against past results, and limits plus hopefully can make suggestions if action is required. Review also the information provided by and available from your equipment and lubricant supplier. If the latter cannot, perhaps review the current selection process. Good support should be more important than just price.

 The following is a list of some sources.

  •  ASTM  and many other standards have advantages in that they are prepared by industry and supplier representatives plus are reviewed regularly. ISO standards, other industry related and national standards can also be very helpful.
  •  ASTM 6224 – 22. Standard Practice for ln-Service Monitoring of Lubricating Oil for Auxiliary Power Plant Equipment. Included are Gear Oils, Hydraulic Oils, Diesel Engine Oils, Turbine/Circulating Oils, Air Compressor Oils, EHC Esters, and EHC Mineral Oil. EHC stands for electrohydraulic control as used in steam and gas turbines. While targeted for power plant applications the information can be applicable to other users.
  • ASTM D4378-20, Standard Practice for In-Service Monitoring of Mineral Turbine Oils for Steam, Gas, and Combined Cycle Turbines.
  • ASTM D117-22, Standard Guide for Sampling, Test Methods, and Specifications for Electrical Insulating Liquids. This guide describes methods of testing and specifications for electrical insulating oils of petroleum origin intended for use in electrical cables, transformers, oil circuit breakers, and other electrical apparatus where the oils are used as insulating, or heat transfer media, or both

 The Electric Power Research Institute (EPRI) has a number of publications that are available to the public. This includes their Lube Notes which are now issued annually and the Nuclear Maintenance Applications Center: Lubrication Guide, Revision 4 (1019518). The latter is 194 pages and in particular see Table 5-7 Typical warning limits for certain lubricant services. This is for oils used in Diesel Engines, Steam/Gas Turbines, Hydraulic Systems, Gears, and Air Compressors. It is dated 2009 but still has some good info.

 There are also some other ones that can be very helpful as for example the US Army Corps of Engineers. See Engineering Manual (EM 1110-2-1424) 29 January 2016, Lubricants and Hydraulic Fluids, CHAPTER 7 Oil Monitoring and System Sampling and Testing.

 When determining what tests to do on the equipment it is important to test for the properties that are most important to maintain that component’s value to production, safety and the environment. The cost of the lubricant itself is usually orders of magnitude less than the cost of consequential damage and/or undesirable outcomes.