2001 Dodge 2500, 352k, 30k on RT6 CK4

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This oil fill is all new-bottle RT6 CK-4.

From Polaris:
Truck Odometer: 352600 mi
Miles on oil: 30000
8 quarts of makeup oil added.
Fleetguard Stratapore filter.

Wear Metals:
(Element (ppm); 235k, 322k, 338k, 352k)
Iron; 42, 52, 30, 50
Chromium; 3, 3, 1, 2
Al; 4, 5, 3, 4
Cu; 3, 4, 1, 2
Lead; 9, 31, 4, 7

Contaminants:
Silicon; 6, 13, 7, 9
Sodium; 8, 6, 5, 4
Potassium; 62, 0, 1, 1

Multi-source metals:
Moly; 75, 76, 5, 4
Boron; 83, 38, 112, 69

Additive metals:
Mag; 1333, 1198, 179, 163
Calcium; 960, 1111, 2174, 2198
Phos; 1138, 1104, 1012, 1048
Zinc; 1439, 1471, 1277, 1271

Fuel Dilution; Soot; Water;
KV100 (cSt); 15.1, 15.1, 15.3, 15.3
TBN; 6.54, 6.99, 5.69, 4.27
Oxidation; 15, 16, 14, 14
Nitration; 10, 10, 9, 9

Polaris Comments:
Flagged data does not indicate an immediate need for maintenance action. (Besides that, nothing useful. They still haven't caught on that CK4 RT6 is different from CJ4 RT6.)

The wear metals are all low, and the Lead spike seen at 322k seems to be nothing but a bad memory.
Based on these numbers, I think I can extend the next OCI. But what would be the governing factor, wear metals or TBN?

Wear Metals. The Iron reading of 50 needs to be corrected based on the 8 quarts of oil added during the OCI. Since I run at an average sump volume of 10.5 qts, that means that 77% of the oil in the system was replaced, diluting the wear metals concentration. The corrected Iron reading would then be 50 x 1.77 = 88.5. A safe number for Iron concentration is 100, but I have seen it pushed to over 120. The limit of 100 would indicate that I could extend another 14%, making the OCI target 34k miles.

TBN. The CK4 version of RT6 looks to be weaker on acid neutralizing capacity. Polaris recommends that the oil be changed at 35% of virgin TBN. Unfortunately, the VOA I had them do on CK4 RT6 did not include a TBN number. I estimate that the new RT6 has a TBN of 7.6. (How did I get that? Assuming that TBN is proportional to the sum of 2*Mg + Ca. Old RT6 had 2*mg + Ca of 3500. New RT6 has 2*Mg + Ca of 2500. 2500 is 28% less than 3500. Old RT6 had a virgin TBN of 10.6. 7.6 is 28% less than 10.6) Therefore, the TBN could be run down to 35% of 7.6, which is 2.66. The TBN of 4.27 from the latest UOA still has a lot of miles left in it. The TBN only dropped by 25% from the mid-OCI reading 15k miles ago, and another 25% drop from 4.27 would still above my estimated limit of 2.66.

My prediction is that Iron will be the limiting factor on the next OCI.

KV100 readings are rock-steady.
The only abnormal thing from this UOA is the soot reading of 0.4. This is the first time soot has ever read anything more than <0.1 on this engine.
 
Yeah I noticed that you finally have some soot in your uoa. Otherwise the new T6 is in good shape. Are you staying with the T6 or have you made a switch to something else?

Thanks for sharing this info.
 
I'm running T6 on the new oil change interval, and will see how the Iron looks at the end. If the wear rate goes up, I will consider something else. Or maybe I'll experiment with adding ZDDP. I like T6 because I can get it at every WalMart in the country for $21/gallon.
 
I found a VOA on CK4 RT6 posted in May. It shows a virgin TBN of 8.7, so my estimate of 7.6 is off somewhat.
The new TBN condemnation limit would then be 3.05, and would indicate I could run out to 45k miles.
Iron would still be the limiting factor.
 
Iron would continue to be the condemning factor using your formula, but with the amount of make up oil you're adding, you may be able to go farther than you think. Just curious if the oil level was full when you collected the sample or was it down a couple quarts since you knew that it was time to drain (thus having some effect on the TBN and PPM of iron)?
 
It was close to ADD. I always try to drain the oil when the level has dropped to the ADD line. The system takes 12 quarts if I fill to the FULL line, but it seems to me that oil consumption is higher at FULL, so I only fill to 11 quarts. Then I add oil when it gets to ADD. That's why I say the average oil volume in the system is 10.5 quarts.
 
Originally Posted By: A_Harman
It was close to ADD. I always try to drain the oil when the level has dropped to the ADD line. The system takes 12 quarts if I fill to the FULL line, but it seems to me that oil consumption is higher at FULL, so I only fill to 11 quarts. Then I add oil when it gets to ADD. That's why I say the average oil volume in the system is 10.5 quarts.
I have noticed that on some engines.
 
Originally Posted By: CT8
She seems like a nice engine.


It runs great. I just wish I could find a transmission that could withstand the relentless torque. The NV4500 has been out of the truck 3 times since April.
 
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