Any value in getting TBN + TAN of trans oil?

Posted by: dparm

Any value in getting TBN + TAN of trans oil? - 12/09/13 09:55 PM

I am getting my car's dual-clutch fluid changed this Friday. The factory fill will have around 52k on the clock; it is Pentosin FFL-4, and is actually very similar to a Dexron/Mercon ATF, but with GL-4 protection.

Is there any value in getting the TBN and/or TAN measured?

FWIW, BMW classifies it as a lifetime fluid (yeah right).
Posted by: chubbs1

Re: Any value in getting TBN + TAN of trans oil? - 12/09/13 10:04 PM

It would be nice to see how this "lifetime" fluid is holding up and TBN/TAN would be one of the only reasonable ways to check that. It is your money so it is easy for me to say. You are changing it anyway so it doesnt really benefit you to fork out the extra money.
Posted by: Raybo

Re: Any value in getting TBN + TAN of trans oil? - 12/09/13 10:30 PM

Huge value. TAN is very important to see how hard the trans is on the fluid. Tell's you exactly how long that type fluid should stay in the trans before it gets acidic.

I like and have used many times:

wearcheck.com

There the big boys in the UOA business and TAN is always included in there UOA. $25.
Posted by: daves87rs

Re: Any value in getting TBN + TAN of trans oil? - 12/09/13 11:50 PM

Would be good to learn....
Posted by: Donald

Re: Any value in getting TBN + TAN of trans oil? - 12/10/13 07:23 AM

You should get TAN for non engine lubricants.

Its included with tests from Polaris that are around $18.50 when you buy 10.
Posted by: btanchors

Re: Any value in getting TBN + TAN of trans oil? - 12/10/13 07:27 AM

TAN would be very valuable, but TBN not valuable. The reason is that a transmission is a "closed" environment. In an engine, one of the oil's jobs is to neutralize the acids that form as a result of combustion gasses "leaking" past piston rings into the oil. In a transmission or differential, the lubricant does not have this function as nothing "leaks in" that causes acid to form - so the lubricant doesn't need to neutralize acids.

However, if a lubricant is stressed due to being overheated, its acid level will rise. This is what TAN is designed to indicate.

So - you want TAN, but not TBN. TBN would be a waste of money.

Others more knowledgeable than I - did I get this right? I think I am on target but I defer to the experts out there...
Posted by: MolaKule

Re: Any value in getting TBN + TAN of trans oil? - 12/11/13 03:37 PM

Originally Posted By: dparm
I am getting my car's dual-clutch fluid changed this Friday. The factory fill will have around 52k on the clock; it is Pentosin FFL-4, and is actually very similar to a Dexron/Mercon ATF, but with GL-4 protection.

Is there any value in getting the TBN and/or TAN measured?

FWIW, BMW classifies it as a lifetime fluid (yeah right).


Being it is factory fluid left in that long, I doubt you are going to discover anything useful, except once you see the analysis, you may want to change the OCI.

For FF fluids, I would want to compare the UOA against the VOA in terms of changes in viscosity.
Posted by: martinq

Re: Any value in getting TBN + TAN of trans oil? - 12/11/13 06:46 PM

Originally Posted By: MolaKule
Being it is factory fluid left in that long, I doubt you are going to discover anything useful, except once you see the analysis, you may want to change the OCI.

For FF fluids, I would want to compare the UOA against the VOA in terms of changes in viscosity.

+1 and +1

Can you get a VOA while you're at it?
Posted by: dparm

Re: Any value in getting TBN + TAN of trans oil? - 12/12/13 10:08 AM

Originally Posted By: martinq
Originally Posted By: MolaKule
Being it is factory fluid left in that long, I doubt you are going to discover anything useful, except once you see the analysis, you may want to change the OCI.

For FF fluids, I would want to compare the UOA against the VOA in terms of changes in viscosity.

+1 and +1

Can you get a VOA while you're at it?


I don't have a bottle of FFL-4. It's expensive stuff ($25/L+). I'll dig around and see if anyone has already done a VOA.
Posted by: bruce381

Re: Any value in getting TBN + TAN of trans oil? - 12/13/13 08:57 PM

TAN and TBN can be used in ATF but you must have a base line to work from