Significance of Lubricant Testing

[materialsguy]

I am attempting to modify our testing procedures to eliminate routine QA testing for lubricating oils, greases, hydraulic oils, etc. Typically, these products are purchased by our maintenance sections for use in Department vehicles and equipment. We typically run flashpoint, viscosity / viscosity index, and pour point.

On a typical product, will these tests really give any good information? Can a company manipulate these numbers (mainly viscosity and pour point) to pass specifications while using cheaper materials? My speculation is that the testing we perform won't make much of a difference if we specify products listed on the API website of licensed products. If we eliminate testing of these products, we will have more room for other, more important testing equipment.

Also, for large diesel engines (ferry boats) will something like Total Base Number, possible TBN after 500 hours of use, give a good indication of quality for these harsh engine uses?

Thanks.

Jason Davis
Louisiana Dept. of Transportation
Materials Laboratory

 

[romke]

i think you are repeating the tests that the manufacturer of the product already did to check production. if the manufacturer is reliable - and most of them are - there is not much need for retesting.

one other thing to bear in mind is that these tests are only simple checks to see whether the product conforms to some simple measurements - and they are certainly not an alternative to the extensive (and very costly!) bench engine testing that is required for API or ACEA approval.

In other words: what you are testing now will very rarely show any anormality, and is no indication of quality whatsoever.

 

[25362]

Materialsguy,

Quality assurance, aka QA, is an expression used by oil manufacturers operating under the ISO 9000 regulations. If the supplier is accredited under one of the QA systems, and most are, one could trust in that the purchased products answer to reported specs and avoid re-checking them in one's labs.

However, we should remember that even "functional" lab bench tests, although valuable as predicting tools on how a specific lubricant will perform under variable operating conditions in full-size machinery, are not infallible or foolproof.
In fact, it is usually on the basis of the lube behaviour in the end-use item that many OEM will "recommend" a brand name to be used in their equipment.

Having said that, I agree with your lab bench testing suggestion in addition to the more conventional tests to be carried out on "used" oil samples. I've read elsewhere that even ASTM recommends carrying out TBN testing on samples of oil taken from the crankcase to check the level of remaining alkalinity in marine diesel engine oils particularly when high sulphur fuels are used. Same samples could be submitted to testing of viscosity, flash point, sulphated ash, pentane and benzene insolubles to verify the suitability of the oil for further service. Good luck.

 

[materialsguy]

Thanks for the information. This is pretty much what I figured. Now I just have to convince a few nay-sayers that we can actually increase our quality assurance by decreasing our own testing.

Thanks again!



Jason Davis
Louisiana Dept. of Transportation
Materials Laboratory

 

[rudyhiebert]

Reputable oil and lubricant manufacturers should show or give specifications that will have all that information. If you want to doubt their product, that's another issue. Testing these oils after they've been in use is also useful.

 

[Xtrema]

Far better to verify used oil condition and take corrective action than to doubt incoming quality. I would spend the department's money on preventive analyses and revised oil change interval specifications.

 

[crowie]

You should test the oils coming in ie new, to obtain baseline results for comparison against used oils.
Used oil testing is critical in expensive and critical components.
Speak to your lube supplier as to what tests should be performed to give you the information you need.
As a guide test engine oils for viscosity @100 deg C, wear metals by ICP, TBN, Soot level, PQ and fuel dilution by flash point or GC.
TBN retention is important but more so if using high sulfur fuels.

 

[jmw]

You may want to add

http://www.practicingoilanalysis.com

to your favourites

 

[plasgears]

There is no substitute for testing your product with various lubes. I found dramatic differences between semi-synthetic greases and synthetic PAO greases. The PAO won every time. Cold start was very agreeable with the PAO. The semi-syth packed gearbox would not budge at -40C. Not so with PAO. We standardized on PAO greases.

 

[widman]

Double checking the lube when it comes in is basically useless in a market with decent lube suppliers. If the analisis is going to be done to check, it should be complete to determine cleanliness and level of additives. That becomes your basline for analisis of the used samples. It also becomes your basis to see whether the oil is "meeting" or "exceeding" your needs. There are hydraulic oils on the market with 250 ppm of zinc ans others with 500 ppm. In high pressure sistems you will generally get much more life out of the latter.
But oil analisis is really about determining maintenance intervals and proactive maintenance opportunities, discovering problems before they become major issues or stop production.

 

[jmw]

Most specifications have a degree of manufacturing tolerance in them. For example, the viscosity of a lube is defined at 40degC and 100degC. The standard or specification for the oil determines what these values should be. However, there is a tolerance to them. Each individual batch of lube will have different characteristics to the next but will still be within tolerance. However, the tolerance might or might not make the difference when you are expecting to use viscosity as an indicator of acidity change, for example. Most viscosity limits are quite coarse. I think 10% change is considered a warning level and 15% critical when looking at viscosity. SO the tolerance is usually quite acceptable.
Testing used oil quality is one thing. Testing oil quality as it is received is another. If you are talking about ferry boats etc then how is your oil delivered? if it is in factory sealed drums, testing may not reveal much useful data. If it is delevered from a fuelling barge, from tanks on board, then testing as received may be valuable simply to confirm that what you have ordered is what has been delivered.
Other than that, if you have been testing oils on receipt then you should have plenty of historical data to tell you whether this information has brought any greater benefit than relying on the original oil specification.