Red Line D6 ATF, 28k mi OCI, 80k mi '13 CTS-V

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All mileage is in kilometers not miles. TBN seems a bit high. What does TBN mean with ATF vs TAN in engine oil?

Note from slip: 48 hours of track time on this oil during the spring/summer and fall of 2017 plus regular driving otherwise.

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TBN is generally more appropriate a test for engine oils, as it tells you a bit about acid neutralization capability. TAN is normally used in gearboxes and transmissions, as it tells you a bit about acid build-up. You can ask for either test for either type of fluid, but this is the convention.
 
TBN goes down over time / use. TAN goes up. Watch TAN in a gearbox or transmission. Those items aren't exposed to combustion or blow-by, so TBN isn't a big 'thing' with them. However, acids can still form and build over time, so that is why TAN is normally watched there. I wouldn't even comment on TBN in an ATF or a gear oil, since it's not typically what the labs watch.

I believe I have sampled the ATF in my Honda twice. Once at ~10k on the vehicle (so factory-fill DW-1) and once at ~57k miles. Both times the TAN was 1.12. The second sample had a certain amount of D6 in it, but was mostly DW-1.
 
Bulwnkl is spot on on relevance of TAN in assessing gear train oils conditions .
In engines applications , SoJ has commented no worry on high TAN like 5 , unless its 8ish to 10.
I don't know what TAN is considered high/excessive in your ATF, my hunch is 2.9 TAN shouldn't be worrisome.
Instead I would speculate this 45k km D6 ATF is still serviceable, IDK.
Yep, it may be nice to see what BStone has to say on this.

This LV RL D6 has a very good viscosity retention capability from its virgin KV@40*C 30.7 cSt, KV@100*C of 6.4 cSt.
I would seriously consider a thicker D4 ATF in say, Red Line with its higher KV@40*C of 34 cSt, KV@100*C of 7.5 cSt in any typical ATF applications including yours .
This may possibly enable you an even longer OCI, or longer track time hours whilst possibly lowering further metal wear rates in 57 ppm in Fe and Cu etc.

Btw, the previous 2 OCI are on RL D6 too?

Edit:add notes.
 
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How would a thicker ATF lead to lower wear metals? Is it because it is thinning too much at the higher temps? I do have a transmission temperature gauge and on track use it does go around 90-100C (194F-212F). Under street use it maybe reaches up to 80C (177F) when idling and 50C (122F) when driving due to the airflow cooling the transmission pan better (I'm assuming).

The previous OCI was RL D6, but the one before that was Total FLUIDMATIC G6 SYN ATF.

Since, this last ATF change only changed half the fluid (6.5 qts out of 13), I'm going to do another drain and fill, to get the newer ATF up to about 3/4 of the fluid.
 
A thicker ATF in RL D4 would've provided you additional 12-17ish % MOFT than a D6, reducing duration and severity of boundary lubrication regimes, shifting it towards mixed lubrication regimes >> EHD lubrication regimes ... in particular during track use and high torque/load low rpm, high temperatures operating range,
hence possibly reducing metal wear rates and less 'thrashing' of oils, IMHO.
 
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Any negative effects with respect to running this with colder weather?

I was going to drain and fill another 6qt to get more old fluid out before track use. I could use D4 instead of D6 ATF instead.
 
I don't think so.
It's like a thinner 0W16 in D6 vs a thicker 0W16 in D4 , and you're unlikely to notice any fuel economy difference I speculate .
 
Okay. I'll add D4 so it should be about half the transmission's fluid capacity for the first track event. Come winter, I'll probably drain and fill 6qt of D6, since I have some left over. Once I run out of that, I have to decide whether to switch between D4 and D6 for the track use vs winter daily driving or stay with D4 all year round .
 
Originally Posted By: Emperors6
Okay. I'll add D4 so it should be about half the transmission's fluid capacity for the first track event. Come winter, I'll probably drain and fill 6qt of D6, since I have some left over. Once I run out of that, I have to decide whether to switch between D4 and D6 for the track use vs winter daily driving or stay with D4 all year round .

+1
The test of the pudding is in the eating.
A UOA/blotter, with its limitations, may throw some light whether a thicker D4 will enhance the components wear performance in your context.
Monitor and assess the difference, if any, with your eyes wide open and a thinking brain.
 
Originally Posted By: Emperors6
How would a thicker ATF lead to lower wear metals? Is it because it is thinning too much at the higher temps?


It would not help in any way.

The D6 does not shear down to 4.5 cSt as did the older DexronIII(H) because of the shear stable additive components.

Keep draining and refilling as your report looked pretty good. I would shorten the OCI as the vehicle gets older.
 
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