About TBN

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I was at a car rent office yesterday, the owner is a friend and people from ARAL lubes came in to give him an offer for the rental cars of his fleet. I wrote down what the ARAL tecnical manager said about TBN: "TBN, Total Base Number, is based on a sulfonate (such as calcium sulfonate and sodiun sulfonate) that helps neatralize sulfur in fuel. TBN is excellent to combat sulfur but its side effect is leaving a hard carbon deposit on engine parts. Therefore higher TBN oil does not mean it better than lower TBN oil. Each oil is engineered to do a certain job for each type of engine. Normally, TBN for gasoline engine oil is around 5 TBN and 9 TBN for diesel engine oil. Diesel fuel contains a lot more sulfur than gasoline. Some fuel such as bunker fuel contains even more sulfur which required as much as 40 to 60 TBN to neutralize sulfur in it but this 60 TBN oil does not work well in gasoline engine. Even a long life drain oil for new specs (VW, MB,GM) doesnt have a higher TBN then 5-6" Is this true? I thought a high TBN is better for gasoline.
 
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It's not higher TBN is better. A higher TBN for UOA means with other factor's such as low wear, silcone, and higher antiwear addives such as zinc, moly, to name the popular ones. This will help with deciding your OCI. It's the retention of TBN that matters most.
 

Praticoman

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So what the ARAL people said was true, yes? What I cant understand is how can a long life oil with a TBN 5 can go up to 15.000-20.000 km? [Confused]
 
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I can understand higher TBN leading to increased piston top deposits and detonation. But carbon ?
 

Praticoman

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quote:
Originally posted by dave1251: I never said that I am an expert but the ARAL junk about TBN leaving carbon deposites sounds like bull.
But still, can a TBN 5 go as much as 15,000km?
 
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"Organo Metallic" detergent/dispersants like Calcium and Magnesium produce metallic ash when they are burned. This metallic ash contributes to carbon deposits on the tops of the pistons and in the piston ring grooves. The zinc in ZnDTP does the same thing and this is what the ARAL guy is referring to. The low TBN, long drain oils (BMW LL-04, MB 229.51, VW 505.01, etc) are only possible since the advent of very low sulphur fuels - both 15 ppm, Ultra Low Sulphur Diesel (ULSD) and lower sulphur gasolines sold in Europe. TS
 

Praticoman

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quote:
Originally posted by TooSlick: "Organo Metallic" detergent/dispersants like Calcium and Magnesium produce metallic ash when they are burned. This metallic ash contributes to carbon deposits on the tops of the pistons and in the piston ring grooves. The zinc in ZnDTP does the same thing and this is what the ARAL guy is referring to. The low TBN, long drain oils (BMW LL-04, MB 229.51, VW 505.01, etc) are only possible since the advent of very low sulphur fuels - both 15 ppm, Ultra Low Sulphur Diesel (ULSD) and lower sulphur gasolines sold in Europe. TS
Thanks for the info TooSlick [Wink] So I guess even a oil with low TBN can be as good as one with high TBN.
 
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quote:
Originally posted by TooSlick: "Organo Metallic" detergent/dispersants like Calcium and Magnesium produce metallic ash when they are burned. This metallic ash contributes to carbon deposits on the tops of the pistons and in the piston ring grooves. The zinc in ZnDTP does the same thing and this is what the ARAL guy is referring to.
If the base stock has a very high flash point, or a low NOACK (a difficult value to find in most cases), then there will be less metallic ash, right? And if UOA doesn't show much decrease in the Calcium, Magnesium, Phosphorus, and Zinc, wouldn't that be a sign that the additives are not burning off and producing ash? Then, isn't it generally as safe as Low SAPS motor oils? Or am I totally out to lunch?
 
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flash pt and noack have no bearing really on "ash" deposits the metalic addtives contribute to that. Dropping additives levels in a used oil are due to dilution or additves fallout as sludge. Not burning up. It is accepted that both additve and base oils "burn" off or leak from the oil system at the same rate and as such unless the metallic additves fall out of solution as sludge (level drops)or make up oil is added (level rises) then the additve level will stay at close to like new levels. bruce
 
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The additve depletion thing NOW brings up the fact that if additive levels stay flat then wear metals must be added to the oil system faster or in higher volumes than they are "burned" there for the wear metal levels are higher by some percent than a UOA leads you to think? or is this wrong? Terry and Ted your thoughts. bruce
 
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quote:
Originally posted by dave1251: I never said that I am an expert but the ARAL junk about TBN leaving carbon deposites sounds like bull.
Perhaps not. If you dig around enough you'll find posts here from true experts cautioning about the use of HDEOs (high TBN, diesel oils) in gasoline engines because of the potential for increased deposits from the detergents. I've been advised that Esso XD-3 *might* not be a good oil to use in my specific engine for that very reason. So while the tendency is choose an HDEO with higher TBN for the purpose of cleaning an engine, it might in fact add deposit.
 
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I'd have no hesitation in using fleet oils in petrol motors. Not really keen on the use of diesel specific oils in petrol engines 'though.
 
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