'95 F250 7.3L DIT, Chev.RPM HD 15W-40 at 11.7K miles

[Bob A.]

Unit Make: 1995 FORD
Unit Model: F-250 Powerstroke, 7.3L DIT
Oil: Chevron RPM HD 15W-40 fleet oil
Additive: Tribomaxx-Mfr.name-"EPConcentrate"
Filter: AMSOIL SDF
Time on oil: 11,686 miles in 12 months
Time on filter: Same

Driving conditions:

2,520 highway miles;
1,310 towing miles--over high mountain passes;
7,756 in-town miles: 1 mile to work; 12 to 15 minute town, i.e., severe on a Powerstroke diesel.

The first data column on the left represents a 4 month drain of Delo 400 15W-40 at 3,700 miles on oil and on OEM filter. Middle data column is the current report data for the RPM 15W-40 plus Tribomaxx additive with AMSOIL SDF filter. The third column is Wear Check's abnormal wear guidelines info. specified for the 7.3L DIT engine.

Purpose: To find a lube which will protect my engine as much as possible, given the in-town driving scenario I described. The Tribomaxx additive is designed to upgrade and maintain TBN over extended periods. The data would indicate that such is the case. The formula for this additive incorporates the use of a calcium petroleum sulfonate. Accordingly, figures are high for calcium and sodium in the UOA data

Worrisome result: The potassium figure makes me nervous, although it wasn't enough to trigger a glycol test at Wear Check. The Wear Check technician said that at the potassium level indicated by the results, it would be nigh onto impossible to trace a glycol leak of that proportion, that is, hard to detect at only 19 ppm. I'm going to do a UOA of my fresh oil at 3,000 miles to see if potassium is still present. I have been monitoring the coolant level since the test, and it has not gone down since I changed oil two weeks ago.

I did have an external coolant leak two months ago. The source was not perceivable, so my mechanic did a cold pressure test to find it, which he did and then repaired it with a new thermostat housing and gasket. I just wonder if the pressure test forced some gylcol through a weak spot in a seal or gasket when the engine was cold? Just one more consideration.

Chevron formula changes: The Boron and moly figures are indicative of changes in Chevron's new formulae for both the Delo 400 and the RPM oils. These additions, plus some other tweakings, have enabled these two oils to meet the CI 4 Plus criteria. Delo and RPM were both licensed in September of '04, but were on the market as CI 4 products before they were licensed as CI 4 Plus.

What is your take on the oxidation, nitration and sulfation results? Wear Check didn't give me abnormal wear guidelines for these effects. I don't have any idea as to what the abnormal levels would be for this engine. Any ideas?

I did change the oil despite Wear Check saying that it was good to go beyond the 11.7K mile point. Without knowing more than I do about these things, I was concerned about the potassium and the oxidation levels.

code:

---

4/27/05 Abnorm.

5/12/04 RPM wear

Delo 15W-40 limits

15W-40 w/ add. for 7.3L

3700 mi 11686 mi. DIT

-------- -------- --------

Silicon 4.4 11 20

Potassium 2.4 19 40

Sodium 3.6 201 60

Fuel %
Glycol --- --- K+NA limits

Water %
Soot % 0.0 0.1 2.0

Sulfation 20 43 --

Nitration 30 55 --



Boron 1.1 35 --

Barium 0.2 0.0 --

Calcium 2921 5630 --

Magnesium 13 12 --

Molybdenum 1.5 27.0 --

Sodium 3.6 201 --

Phosphorus 1154 1113 --

Sulfur 4424 4560 --

Zinc 1257 1208 --

Visc@40°C --- --- --

Visc@100°C 14.2 13.04 --

Oxidation 50 85 --

TAN --- --- --

TBN 10.1 16.6


Iron 13 36 250

Nickel 0.7 1.7 8

Chromium 0.6 1.5 30

Titanium 0.0 0.5 --

Copper 0.0 2.2 50

Aluminum 2.3 4.7 30

Tin 0.4 0.0 20

Lead 2.4 5.7 50

Silver 0.0 0.0 20

---

 

[Pablo]

The tribomax sure did boost your TBN!

Too bad you don't have a VOA. I really wonder if the K and Na came from the Tribomaxx additive(?)

Wear metals pretty much follow the mileage.

Oxidation is hard to peg and I'm not familiar with WearCheck's methodology....seems like a 50 at 3700 miles is high, but if the scale is 200.....and then it's 85 at 11700 miles.....dunno, but it's relative and it's not a straight line. Again a VOA is helpful.

 

[TooSlick]

Did you know that if the TBN gets too high, you can see corrosive wear from making the oil even more alkaline? Motor oil chemistry is a careful balanced act and you should not play organic chemist in your garage.

Delo 400, 15w-40 is an excellet product and the idea that someone off the street can measurably improve on it by dumping in a can of snake oil is simply nonsense...

I'd run some Delo 400 for 10,000 miles without the TBM and see if these results don't improve!

TS
Tooslick

 

[Pablo]

NaOH and KOH will of course boost your TBN!

 

[Bob A.]

Pablo,

I spoke directly with a Tribomaxx manufacturer representative who stated that they do not use potassium as an additive. He confirmed that their formula has a lot of calcium and sodium. The Wear Check technician also confirmed that Tribomaxx has high concentrations of Ca and Na because. Wear Check does many UOAs for Tribomaxx customers and have to flag these samples for some extra scrutiny or they'll misinterpret the results.

I also spoke with a Chevron rep. here in town. He looked up the additive package for RPM 15W-40 and confirmed that potassium is not in the Delo or RPM formnulas. So, it's a very strong possibility that what potassium has shown up in this UOA summary is from within my engine somewhere. I'm nervous about that.

Switching topics here: the wear metals do pretty much follow the mileage from the Delo sample to the RPM UOA, but, as you pointed out it's not a straight line comparison. Both time on oil and mileage for the RPM/Tribmx. sample are 3 times that of the Delo mileage and time on oil. If we do the straight line exptrapolation, many of the wear figures for the RPM oil are actually less than 3 times what they were for Delo, running a range of, say, 1.8 times more up to say 2.5 times -- depending upon which item we're looking at. Given the severe driving conditions characteristic of the 12 month sample period for the RPM/TBM, I'd say this was a pretty good report. In the first place, I didn't think the Delo results for 4 months and 3700 miles were all that rockin' hot.

All that said, I've been impressed recently with some Delvac 1300 Super UOA results presented on BITOG, and they have prompted me to change my approach a bit. My plan for the next year and a half includes the following:

1. Do a 3000 mile UOA of the fresh RPM 15W-40/TBM combination to determine if the potassium is still present at the same or higher levels recorded for this current report. This data will also be good for a comparison with the baseline results obtained from the 4 month Delo 400 sample of 4/27/04.

2. If the sample is O.K. with respect to the potassium, then I'll run the drain period out to 7500 miles, take a sample and then change oil to Delvac 1300 S and add Lube Control. I think LC does a similar job as the Tribomaxx.

Now, don't scorch me because of what I just said about LC.

I'm not implying that LC is the same as Tribomaxx, but LC is supposed to improve oil performance, and one of its ways to do that is to strengthen and stabilize the TBN, which is the main effect I was after from the Tribomaxx. Remember, I've got continuous severe driving conditions I'm trying to mediate.

Besides, LC is a tried and true product with a substantial history of positive results behind it. Too many on BITOG have praised its value for me not to consider it. Besides, Too Slick, this approach would address the concern about too high of a TBN that you expressed in relation to Tribomaxx -- and still enable me to strengthen my lube as needed.

3. If the 3000 mile sample shows an increase in potassium, then I'm going to huddle up with my PSD mechanic and find out what the **** is gong on with my cooling system.

Thanks for your input, guys. Any further thoughts or suggestions?

Bob A.

 

[Pablo]

Just a quick comment on the K. If there is no K added then you should find out if you have a coolant leak.

 

[TooSlick]

Pablo brings up an excellent point!

These PSD's have a "wet sleeve" design, which can lead to cavitation damage and internal leaks, through the wall of the coolant jackets for the cylinders. If this one hasn't been well maintained by adding SCA's to the coolant periodically, it's very possible this is a small leak.

TS

 

[Bob A.]

Yeah, I know about the potential cavitation problems, TS. I recently had the coolant SCA level checked, and the litmus-like tests did indicate the concentration was excellent.

I bought the rig at 95,000 miles and I don't know if the coolant was maintained well by the former owner. I know I have taken care of it, but who knows about the other guy? The rig has 145,000 miles now.

My next UOA will determine a whole bunch about the elevated potassium -- and what steps to take if the problem persists.