Rotella T6 in a Cummins Dodge 2500, sample #2

[A_Harman]

Truck Odometer: 205300 mi
Miles on oil: 18000
2 quarts of makeup oil added since last oil change.

From Polaris Labs.

Wear Metals:
Iron; 60 ppm
Chromium; 4
Al; 5
Copper; 6
Lead; 4

Contaminants:
Silicon; 11
Sodium; 15

Multi-source metals:
Moly; 76
Boron; 39

Additive metals:
Mag; 1193
Calcium; 1114
Phos; 1188
Zinc; 1451

Fuel Dilution Soot Water
KV100 = 14.8 cSt
TBN = 6.46
Oxidation = 13
Nitration = 9

Polaris Comments: Data indicates no abnormal findings. Resample at normal interval.

I swear I've driven this thing 6000 miles between samples, but oil just won't show it! The only thing that has markedly increased is Iron, going from 41 to 60 ppm. At this rate, it will be ready for changing in another 12,000 miles if I hold to a condemnation limit of 100 ppm. I have never gone longer than an 18k OCI, so I'm getting into uncharted territory. Does anybody see any reason I can't go to 30k?

If I'm going to stretch the oil that long, should I change the filter before then? Just make an annual filter change, and change oil when Iron hits 100?

I talked to Polaris Labs, and the tech said their change recommendation for TBN is at 35% of new, which would be 3.7. At the average rate of decrease, TBN would hit that limit in another 29k miles. I don't think that TBN will be the limiting factor on this load of oil.

 

[abycat]

sweeet! I would say 22-25,000 is a go but 30,000 might be getting a little past the loose sleep mileage. Im sure if you tried it once to get the sample it would not shorten the life of your engine by any measurable amount. Im not sure every number for the wear is linear but if it was you would have some good looking numbers. I just think that a uoa doesnt tell all and oil does behave differently with more and more miles.

Oh and a quart every 9000 is pretty cool. Id love to see your UOA at 30,000 that would be neat with the other data you have already. What year and what mods if any does your truck have??

 

[LeakySeals]

Whats equally remarkable to the UOA is your oil consumption. 1qt every 9k on a 2002 with over 200k. Wow. Have you used T6 exclusively on the engine?

What kind of filter are you using? whats the rating? Will you be crawling underneath within inches of the drain bolt just to change the filter? Or is the filter accessible from the engine compartment?

 

[Doug Hillary]

Hi,
A_Harman - Fe at 100ppm is quite low for a sole condemnation limit. Typically and depending on the engine family it is around 150pp to 200ppm. Of course in use the PPM level will "grow"

Look for an incearse in other wear metals that may increase in consort with rising Fe levels - this is what UOAs are all about as far as wear metals are concerned

The TAN/TBN ratio or other factors may overwhelm the Fe level first

 

[roadrunner1]

I surely wouldn't change the filter, it looks to be doing its job.

If I were you I would follow the Polaris recommendation, resample at your next determined interval.

Out of my own curiosity do you have an hour meter or know how many engine hours you have run on this OC?

 

[dnewton3]

Outstanding!

Great to see someone actually use a syn for the proper purpose of greatly extending the OCI! Happens so infrequently here, it's almost cause for celebration.


As for your condemnation limits, I'd say that 100ppm would be fair, but towards the lower end, as Doug mentioned. Point is that if Fe is the only item that is anywhere near condemnation, then perhaps a bit longer run could be utilized. The concern often comes when several items (say TBN, wear metal, soot, oxidation, fuel, etc) would be nearing condemnation together; that makes for a more clear decision to OCI. Overall, if Fe is the sole item that nears the limit, it can be carefully be pushed out a bit. I think that is what he was getting at, and I agree. If Fe is the ONLY issue in your UOA that nears, then perhaps 150ppm is closer to a real limit. And it's likely that as it increases, you might see a small change in the Cu and Pb as well. That is what would indicate a very real shift, and a very clear indication to change oil.

As for the filter, I would say that if you get to 30k miles, and the oil itself still looks good, then perhaps a FCI might be warranted, but I have no idea what brand/model of filter you're currently using. Whatever it is, it seems to be sufficing well. Of course, this is kind of like the whole chicken/egg conversation; is the oil in great shape because the filter is doing such a great job, or is the filter not being heavily loaded because the oil is controllling things so well? At some point, one also has to credit this one engine for running so cleanly. If you can make it to 30k on the filter, then perhaps a FCI is due as a precaution? That would also have a benefit of slight bit of top-off as well.

I see no reason whatsoever that you could not make it to 30k miles overall. If you do get cold feet, then take another sample at 25k miles and see how you're progressing. At this progression, 30k miles is easily doable, and probably could be pushed out even further, with UOAs along the way. How are you getting the samples? Fumoto valve or sample suction tube or sample port?


Again - congratulations on a solid program of using synthetics for their entended purpose. Your rig is in great shape'. I see every reason to continue the current load in your program and no reason to OCI.

 

[A_Harman]

Oops, sorry, but my original post had a mistake in it. It should have said "2 quarts of makeup oil added since the last oil sample", not "oil change". The engine burns oil at a steady rate of 1 qt / 3000 miles. So since the last oil change, I have added 6 quarts, which is probably a big reason why everything is staying so fresh.

 

[A_Harman]

Originally Posted By: abycat
What year and what mods if any does your truck have??


I have a Superchips tuner that I run on the +40 HP tune, +50 HP injectors, a stock VP44 pump, K&N panel filter, stock turbo turned up to 27 psi, and a 4" exhaust. The truck puts out 290 HP at the wheels, so in terms of what other guys have done to their Cummins', mine is mild. I put a GearVendors overdrive on the truck a few months after I bought it in 2003 to bring engine speed down on the highway. At 75 mph, the engine is humming lazily at 1700 rpm with my 35" tires.

 

[A_Harman]

Originally Posted By: LeakySeals
Wow. Have you used T6 exclusively on the engine?

What kind of filter are you using? whats the rating?


This is the first OCI on RT6. Before that, I ran a short interval with M1 TDT, and dumped it early because of high consumption, and because RT6 looked a little stronger in a few different areas, and is slightly cheaper to boot. Before that, I ran VPB Classic 15w40 on one-year intervals for many years. This mostly meant 15-18k OCI's.

I'm running a Purolator PurOne filter.

 

[LeakySeals]

Wonder why the zzdp listed exceeds 1250ppm, what most VOA's and UOA's show hmmm...