TBN behavior

[3 Mad Ponchos]

I've been doing a lot of research on TBN to determine why it's been unchanged for the last three samples in my oil study.

It seems that TBN is expected to drop from its virgin sample and then reach equilibrium, and it can hold equilibrium for quite a while (in fact some tests I reviewed indicated that the viscosity went out of spec long before the TBN caused a problem). What I haven't been able to find is exactly what is at equilibrium -- what forces are at work here and how are they in balance?

This certainly is an interesting twist to the test. I can't wait to see how long the equilibrium holds out. I'm going to add a sidebar discussing TBN in detail once I have enough info for it. I have some technical papers in the mail.

Cheers, 3MP

 

[Patman]

Don't discount the half quart makeup oil after each sample though too Brian.

Here is the link to Brian's oil life study, for those that don't know about it:


http://neptune.spacebears.com/cars/stories/oil-life.html

 

[turbochem]

Although I'm not expert on TBN...I'm thinking it might act a bit like a titration curve.

At the begining of a weak base/strong acid titration (where the base is being titrated) the pH drops fairly quicly until you reach the "buffer zone," where the pH begins to level off. Then, as you approach the equivelence point (the point where all the base has reacted), it dramatically drops again....

Just a thought.... Sample Titration Curves

See Strong Acid v Weak Base titration down on page....

 

[3 Mad Ponchos]

Nice link, thank you!

This is in line with other studies & reports I've been reading, which demonstrate TBN hitting an equilibrium point where it stays fairly steady for a while before suddenly dropping off.

I'll have more details on this after I get some more reading done.

Cheers, 3MP

 

[3 Mad Ponchos]

Can anyone describe how test results are interpreted, how repeatable the test is, and how accurate the results are?

Basically I'm fishing for some guidance as to how much reliability I can expect from TBN testing.

Cheers, 3MP