TBN 1.0

[Radman]

My lubrication class circa 1980’s discussed Total Base Numbers (TBN), & Total Acid Numbers (TAN). A TBN less than ½, and greater than 1/3rd of starting TBN was considered optimum OCI. Therefore if the virgin oil contained a base TBN of 10 the OCI should be performed between 5.0 – 3.3 and no less. The TAN increased significantly once ½ of the TBN was consumed.

I have been reading the Blackstone recommendations to change at a TBN of 1. I don’t understand why a respected laboratory would want the oil to contain such high amounts of wear causing acids? Is it a game to have customers to continue UOA’s to extreme mileages, and tell them how great they are doing? “Your engine is the best in the world. Your TBN was 1.8 at 11,000 miles, try 12,000 miles next time”. I don’t understand the mindset on seeking the 1.0 TBN.

1.0 isn’t a Grail… it is a Fail!

Can someone enlighten me?

~ Radman

 

[javacontour]

As long as an oil has a non-zero TBN number, doesn't it mean it's still neutralizing acids?

Isn't TBN a measure of the oils ability to neutralize acid? So it's not like the acids that have been neutralized are still acids. It's my belief they are not suspended as acids, but at "neutral" compounds.

When the TBN goes to zero, then you are no longer neutralizing any acids created in the engine.

But perhaps my understanding is incorrect...

 

[Radman]

Originally Posted By: javacontour
As long as an oil has a non-zero TBN number, doesn't it mean it's still neutralizing acids?

Isn't TBN a measure of the oils ability to neutralize acid? So it's not like the acids that have been neutralized are still acids. It's my belief they are not suspended as acids, but at "neutral" compounds.

When the TBN goes to zero, then you are no longer neutralizing any acids created in the engine.



But perhaps my understanding is incorrect...


Low TBN reserves provide insufficient acid neutralisation capacity leading to corrosion of engine components particularly around the piston ring pack, piston ring lands and top end bearing. Fouling of the engine internals and under piston cooling ways will also increase.

 

[Quattro Pete]

Originally Posted By: Radman
My lubrication class circa 1980’s discussed Total Base Numbers (TBN), & Total Acid Numbers (TAN). A TBN less than ½, and greater than 1/3rd of starting TBN was considered optimum OCI. Therefore if the virgin oil contained a base TBN of 10 the OCI should be performed between 5.0 – 3.3 and no less. The TAN increased significantly once ½ of the TBN was consumed.

I have been reading the Blackstone recommendations to change at a TBN of 1. I don’t understand why a respected laboratory would want the oil to contain such high amounts of wear causing acids?

Circa 1980s, there was a different method (ASTM D2896) of measuring TBN that resulted in somewhat higher readings. Somewhere around 2005 Blackstone (and many other labs) switched to a newer method (ASTM D4739) which results in lower readings, hence the TBN of 1.0 may not be as bad as it sounds.

Also, as you pointed out, it's not just the TBN alone but a relation to TAN that should be looked at. Since Blackstone typically does not test for TAN, they have no way of knowing. I use Wearcheck and have them test for both. Their general rule of thumb is when the TAN is 80% of the TBN, the oil should be changed. And as you know different oils may have different starting TBN and TAN.

Also, as we've seen with some modern oil technology, TBN does not always tell the whole story.

You may also find this thread of some interest, in case you haven't yet come across it:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2251013#Post2251013

 

[OldCowboy]

Here's what Polaris Labs has to say about TBN levels (http://polarislabs1.com/pdf/optimizing-drain-intervals-using-tbn-vs-tan.pdf):

"...in reality, TBN depletion can reach about 65% before it becomes necessary to change the oil."

It would seem this is yet another strike against Blackstone. Using Polaris' criteria, the only time a TBN of 1 would be acceptable is if the starting TBN was 2.9.

 

[Radman]

Originally Posted By: OldCowboy
Here's what Polaris Labs has to say about TBN levels (http://polarislabs1.com/pdf/optimizing-drain-intervals-using-tbn-vs-tan.pdf):

"...in reality, TBN depletion can reach about 65% before it becomes necessary to change the oil."

It would seem this is yet another strike against Blackstone. Using Polaris' criteria, the only time a TBN of 1 would be acceptable is if the starting TBN was 2.9.


I agree completely with you & Polaris Labs.

 

[Astro14]

Since the Polaris labs TBN vs. TAN methodology specifically refers to diesel oil and diesel engines (thus clearly creating a distinction), how applicable is the TAN vs. TBN approach when analyzing gasoline oil performance?

 

[Radman]

Most fleet UOA's are performed on heavy equipment. Regardless of gasoline, or diesel the outcome of high acids in an engine will be the same.

 

[tinmanSC]

Originally Posted By: Quattro Pete

Circa 1980s, there was a different method (ASTM D2896) of measuring TBN that resulted in somewhat higher readings. Somewhere around 2005 Blackstone (and many other labs) switched to a newer method (ASTM D4739) which results in lower readings, hence the TBN of 1.0 may not be as bad as it sounds.


^ This information is correct. ^
ASTM D4739 is the new standard and in that standard, a TBN of 1.0 is "depleted." It does not depend on starting TBN (this was one of the reason why the test was changed. Having a list of every oil's starting TBN in order to make a correct judgement was unreasonable). This is not a mark against blackstone, as someone claimed, they are using the standard correctly. For conformation I invite you to google ASTM D4739.

 

[Radman]

I googled "ASTM D4739" it doesn't give any limits. Just a description of the test.

http://www.astm.org/Standards/D4739.htm

I still won't let my oils TBN drop past 33% of base

 

[dparm]

TBN depletion should not be the only marker you use to know when oil is to be changed.

If your flashpoint is dropping too far, the oil is getting fuel contamination, etc, those are the other markers. It's a combination of many things.

 

[m37charlie]

I agree completely with the OP.
I've had UOAs with Detroit Diesel and we found in our BMW X5 35d diesel SUV that with the weak C3/MB229.51/LL04 oil (Castrol SLX Professional OE 5W30) used by the dealer, with new TBN ~6.4, that after the computer advised OCI (9-10K mi) TBN got down to 1.5 both times. The one time they measured TAN it was up to 4.8. Detroit Diesel's analyst marked this as "severe", and Fe concentrations were 94 and 83 ppm.
Because of the IMHO severe TBN depletion and weakness, I have changed to Mobil Delvac 1 LE 5W30, an ACEA E6/E4/E7 oil with TBN 12.6 but ash only 1.0%. I know I will pay for it in DPF life, hopefully someone in Anchorage will have a DPF vacuum cleaner by then.

Charlie

 

[INDYMAC]

There are several factors or reasons why a TBN rule of thumb is difficult to use accurately. Why? Because not all engine oil formulas are created equally. Their clean oil chemistry's are all different, their starting alkalinity chemistry's are all different, and their starting acidic chemistry's are all different. So unless you are very familiar with the starting chemistry of your engine oil, you have no idea when it is toast. It is a very complex process that an engine oil goes through during its service life. It is attacked by extreme heat and many harmful contaminants before the end of its service life.

So what is a company like Blackstone to do for their customers that are clamoring for a simple rule of thumb because they are too resistant to pay for a full analysis of the oil? They came up with the 1.0 TBN proclamation. Surprisingly, this rule actually works in some cases where acids were actually kept in check throughout the OCI. But there have been other cases where TAN starts rising rapidly even before the TBN has dropped 50%.

If you really want to know the limitations of your engine oil, then you have to become familiar with the product in its clean state. You might be surprised at the starting TBN and TAN, especially if it doesn't match the typical properties listed on the manufacturer's PDS. Formulas change all the time.

 

[tig1]

For the average engine UOAs are not much value outside of coolant or fuel detection. I have been changing oil every 10K for 33 years in all types of engines with never a concern of engine problems.

 

[tinmanSC]

Originally Posted By: Radman
I googled "ASTM D4739" it doesn't give any limits. Just a description of the test.

http://www.astm.org/Standards/D4739.htm

I still won't let my oils TBN drop past 33% of base

Oh, the files are all pay files. They cost $35. Hrm... I'll see if I find a free source.

 

[Radman]

Thanks Tinman, I will be checking this post for your update.

 

[Gene K]

You should search some of Doug Hillary's old posts. They had engine teardowns (and checked wear) and ran a million kilometers an engine before he got rid of them. With input from Detroit Diesel and Mobil they ended up with condemnation limits of 1.0 TBN and 8.5 TAN on Delvac 1. He ran engines with TBN as low as 0.1 and TAN as high as 9.1 with no sign of additional wear on teardown.

Do not take that as a blanket recommendation. Just open your mind to the fact the limits can be pushed a lot farther than you think with the proper knowledge.

 

[Radman]

I have rebuilt my fair share of engines and have seen what long OCI's can do. The worst I had ever seen was from a 69 Chevy Shortbed that I restored. The 350 engine's lifters retaining clips were destroyed and migrated into the main bearings.

With proper education one will learn that playing the TBN game to 1.0 on an engine you would like to keep for 15 years is a destructive test. I laugh at the taxicab tests were they run the engines 60K in two years with 10K oil changes. Acid eats metal slowly and a two year test is too short.