Acids and TBN

[J]

Hi,

An offline discussion regarding Acids w.r.t
TBN is at an impasse. Alas ... none of us are
chemical engineers.

We have several questions.

First question is whether or not acids attack
base stock. My guess is yes. As 'Kule has
stated, base-stock shears just like VII
molecules. Base-stock is much more likely to
re-assemble itself than VII polymers.

However, an acid can either prevent base stock
from re-assembling itself or simply attack
the carbon-carbon or carbon-hydrogen bonds
because it wants an electron and will stoop very
low to get it!

So, an acid can be neutralized by base
molecules or by the acid molecule attacking
base stock and getting the electron that it
desires?

Is that why TBN drops off sharply at the
beginning of drain interval (such as in 3MP's
oil life study) and looks like exponential
decay? So, if TBN exhibits exponential decay,
will it never reach zero?

Jae

 

[Eiron]

And why is 3MP's TBN bobbing up & down & up like dat?

 

[Patman]

quote:

---

Originally posted by Greg Netzner:
And why is 3MP's TBN bobbing up & down & up like dat?

---

The addition of a half quart of fresh oil every 1000 miles is responsible for his TBN coming up on some of the samples. I'm sure that if his engine didn't burn oil (and as such only 1/4 qt was needed every 1000 miles) then his TBN would be much lower right now.

 

[3 Mad Ponchos]

One of these days I'll get around to writing my article on TBN. I have hundreds of pages of research on the behavior of used oil sitting here but I just haven't had time to put it together yet.

The variation in my TBN is no doubt influenced by the make-up oil to some degree, but the numbers are also within the test's margin of error so the slight variations should really be read as "no change". This oil is still in equilibrium.

Now, what I am about to write is a gross oversimplification, and I'll expand on it sometime in the future when I write the full article.

In one study I have here, TBN lost half its value within 50 hours of operation (by their scale, 1 hour of operation equals 31 miles, so half the TBN was lost in 1,550 miles) and was pretty much at equilibrium from 100 hours to 400 hours (up to 12,000 miles). The oil was pretty well shagged at this point, and its properties dropped off substantially after 400 hours. This test was on a Toyota 1.5L engine using 10W-30 SG oil.

By this study's reckoning, the oil's inhibitors were used up around 100 hours (3,100 miles). TBN's equilibrium was maintaned because the degraded compounds also have inhibitive qualities. However, these are not as effective as the original inhibitors and TAN has a definite trend upward after the 100 hour mark. TAN and TBN stay fairly well in balance until 500 hours (15,500 miles), when TBN is essentially used up and TAN skyrockets.

So, if this study is any guide, we could be in for a long wait on MY study.

I'll try hard to prepare my full article in the coming weeks, as it seems to be a subject with much interest.

Cheers, 3MP

 

[BOBISTHEOILGUY]

Well, instead of going to yours or some one elses site for some answers, why not just visit our articles section that will give a much more elaborated breakdown about TBN and the how's and whys.....

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000045#000000

 

[3 Mad Ponchos]

Ouch, Bob, what'd I do to deserve that?? I was just trying to provide some info!

3MP

 

[BOBISTHEOILGUY]

Sorry, didn't mean anything personal. I was writing a pm to you when I came back I saw your messg.
bob

 

[3 Mad Ponchos]

No worries, it's all good.

Cheers, 3MP

 

[Patman]

quote:

---

Originally posted by 3 Mad Ponchos:
No worries, it's all good.

Cheers, 3MP

---

Excellent!

 

[quadrun1]

quote:

---

Originally posted by 3 Mad Ponchos:


By this study's reckoning, the oil's inhibitors were used up around 100 hours (3,100 miles). TBN's equilibrium was maintaned because the degraded compounds also have inhibitive qualities. However, these are not as effective as the original inhibitors and TAN has a definite trend upward after the 100 hour mark. TAN and TBN stay fairly well in balance until 500 hours (15,500 miles), when TBN is essentially used up and TAN skyrockets.

So, if this study is any guide, we could be in for a long wait on MY study.

---

Interesting intervals there!

1) 3,100 miles is close to the 3,000 mile drain interval promoted by the oil change industry

2) 15,500 miles is the exact mileage that the countdown oil life timer on a BMW 3-series starts out at. The countdown goes down quickly with an increased number of short trips and decreases slowly with long trips.

The most recent analysis of Castrol "synthetic" oil from my dad's BMW showed a TBN of 1.5 after 15,000 miles of use. (No oil added over that interval)

3MP, I'm thinking your oil study can go that far or greater (!) before the TBN gets to 2, based on the fact that you're adding fresh oil regularly. Will you keep going until at least the TBN gets past equilibrium?

Thanks,
Jason

 

[3 Mad Ponchos]

Hi Jason,
Currently my criteria for draining the oil is:
* TBN reaches 2
* viscosity exceeds the limits for a 30-weight oil
* insolubles are no longer controlled by filtration
* wear metals increase at an alarming rate

However, as this is my first oil test, the exact criteria are still up for revision as test results require. I used to focus on flashpoint also, but the flashpoint testing is so broad that I'm not really relying on that anymore; I'll probably reduce its importance when I redesign the page down the road.

I had originally thought TBN would be the determining factor but now I'm starting to think it'll be either viscosity or contamination. I'm also giving up on trying to guess. LOL

Cheers, 3MP