Re: Used Oil Analysis in India Very interesting to see this oil analysis report as well as the blackstone report. Thank you very much for sharing.
TBN although is an important parameter, equally important is Total Acidity Number (TAN). The Base or Alkalinity is required to combat the acidity build up from Sulfur and Nitrogen based acid build ups. Also soot itself has a strong polarity, that needs to be countered. Hence many oils start at a TBN of 7 to 12. It depends on the type of application. As the engine runs, acidity (TAN) builds up and it eats away the alkalinity (TBN) and reacts with seals and metals. Depending on the engine and application the engineers set the oil discard point mentioning the lowest TBN # allowed or the highest TAN # allowed which ever comes first.
The Blackstone report is actually very 'kindergarten-ish'. I might be raising a few eye-brows with that comment. You see in my job we track thousands of engines in the field. We do oil analysis every 10 to 14 days on every engine, both new and remanufactured. Based on nearly 2 decades in engine development, let me post a few counter points to the blackstone report below. Please don't take it as a personal attack. Just trying to clear the air on this report. Please accept my humblest apologies if my comments come across as rather harsh.
1. The age of the engine is not used to segregate wear rate, this is extremely critical. Does older engines wear differently with different oils? What if newer car owners being over-enthusiastic sending more samples. The universal average itself is from the same sample, like a self full-filling prophesy.
2. The emission stage of the engine. Is it Tier2 or Tier4. Lower emission engines run at much higher temperature and pressure. Some have EGR which can increase the wear rate. Study after study by lubrication engineers have shown that, lower the emission requirement, closer to synthetic, the oil needs to be. Taking a grandfather’s engine and trying to compare different oils, then apply that take-away to modern low emission engines is very dangerous.
3. The oil change interval is very low. Consider this along with point #2. You need a very detailed study showing age of engine, preferably in MWhrs and not in miles. Because 2 different drivers can ride 10,000 miles in very different ways. One can use a lot more power, and hence put the oil under much higher stress. So miles do not matter. Engine designers prefer MWhrs not miles.
4. Type of filter used. Cellulose vs Synthetic, absolute filtration efficiency value, type of oil filtration method (same engine can have different filtration in different models).
5. Finally, big corporations have millions of $ to spend on just studying the lube system performance year after year. Smaller firms collecting samples send over mail may not be the final word.
So what you really need is an analysis that shows the engine age, MWhrs between oil change, filter used, filtration method, TBN & TAN difference over oil change interval, actual kinematic viscosity etc. You will be surprised, 2 different 5W-30 oils can have different viscosity. 5W-30 is sort of like a bracket. Also use the same brand of oil for a given engine for say 30,000 miles, I mean don’t keep changing the oil brand at every service. Then drive a correlation. In at least one case (Valvoline 5W/30), you can see extremely high Sodium. Does that mean the engine has coolant leak using a particular oil. This does happen, as certain oil additives react with certain type of seals and let small amounts of coolant into oil, increasing engine wear. Hence companies recommend oil specs for each engine. So what was the conclusion from high Na? If you find Na, then a good oil analyst will also look for Potassium, to confirm coolant leak. But Potassium is missing in the table !
After working in engine design long enough, analyzing tons of data, working with experienced lube engineers, I can very confidently say that - In modern low emission engines, type of oil indeed has a significant impact on engine wear and life.
There is a reason auto companies give oil spec and then keep updating it.
Last edited by Czarcarsm : 16th August 2017 at 22:58.
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