8800 OCI, Chevron Supreme SL 5W-30 with addit.--'02 Outback, 2.5L non-turbo

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May 3, 2005
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Location
Yakima, Washington
Lab--Wear Check, So. Carolina
Vehicle--Subaru Legacy Outback, '02
Engine--2.5l boxer 4 cyl., non-turbo; oil capacity with Baldwin filter is 4.4 qts.
Oil--Chevron Supreme 5W-30 SL.
Additive--Tribomaxx: calcium sulfate which, I believe, is a surfactant, with a good charge of sodium.
OCI--8800 miles.
Filters-- 1. Purolator Premium Plus, 3300 mi.;
2. Baldwin, 5500 mi.
Top-up oil: 0 qts. needed at filter change at 3300 miles, but added about 26 oz. at filter change because some oil stayed in the old filter and also the Baldwin filter is about 6 oz. larger in capacity than the Purolator PP. This 26 oz. of added lubricant included .6 oz. of the Tribomaxx to go with the "top-up" oil. No top-up oil needed at 8800 if I had decided to continue the OCI.
Driving conditions--60:40 in-town:highway; last 1500 miles were pretty much winter driving in town, e.g., 15F to 40F, snow, ice, etc.
code:





Sample Dates 07/28/05; 12/17/05

Silicon 2.1; 11

Potassium 2.6; 0.0

Sodium 83; 78 (the addit.)

Fuel %
Glycol 0.12; ---

Water %
Soot % 0; 0

Sulfation 60; 167

Nitration 45; 175







OIL CONDITION



Sample Date 07/28/05; 12/17/05

Boron 78; 39

Barium 0.7; 0.0

Calcium 3820; 3254

Magnesium 5.2; 9.6

Molybdenum 71; 61

Sodium 83; 78

Phosphorus 694; 714

Sulfur 3284; 3554

Zinc 764; 784

Visc@40°C ---; ---

Visc@100°C 9.83; 10.7

Oxidation 55; 130

TAN ---; ---

TBN 9.63; 5.18







WEAR



Sample Date 07/28/05; 12/17/05

Iron 3.7; 8.3

Nickel 0.6; 0.6

Chromium 0.2; 0.5

Titanium 0.0; 0.1

Copper 2.5; 6.0

Tin 0.3; 0.0

Lead 1.4; 2.3

Silver 0.0; 0.0

Aluminum 0.8; 4.9


Almost all of the metals showed wear at the same rates when comparing the 3300 mile sample with the 8800 mile sample. Aluminum was the one which jumped more than it should have. Might be due to the jump in silicon as well. Time to change the air filter.
dunno.gif


The other items that jumped more than they should have are: sulfation =167, should have been 153 if the sulfation rate at 3300 miles maintained throughout the last 5500 miles; likewise, nitration jumped from 45 to 175. It should have been 115, all things being equal.

I was happy with the fact the potassium burned off through the second stage of the OCI. That which registered in the first analysis was residue from a head gasket issue I had prior to the oil change preceding these 2 samples. The head gasket was replaced on warranty at about 37,000 miles.

I did run this oil 1800 miles more than I should have, even with the additive. I'll keep my OCIs to 5000 to 7000 miles from now on. Despite the analysis results and the recommendation that it could go longer, the oil felt tired to me during the last 1000 miles. Highway mileage went down a bit, maybe due to a dirty air filter -- and possibly the viscosity increase. Engine idle wasn't quite as smooth, and the engine ran a little noisier at high rpms, e.g., when in passing gear.

The cost of the oil is $1.14/qt. from Costco -- up 3 cents from 6 months ago -- and $.50/qt for the Tribomaxx at .5 oz./qt. Total = $1.64/qt. Sure beats the prices of the synthetics, and maybe even some of the performances.

Another point is that this Chevron 5W-30 was the SL, not the SM. We can see that the SL works well with the Tribomaxx, but I'll have to do this again with the SM to see if SM and Tribomaxx are compementary.

The TBN looks pretty good after 8800 miles. That's the Tribomaxx at work.

Any other thoughts?

[ January 04, 2006, 01:24 AM: Message edited by: 59 Vetteman ]
 
Copied below is a post from PATMAN that may shed some great light on the oxidation and nitration numbers and their meaning in this analysis. It would sure explain my feelings that the oil was spent toward the end of the OCI, despite the wear numbers.

Bob A.
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Patman

Administrator
Member # 6

posted March 23, 2003 02:53 AM
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quote:
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Originally posted by '00obw:
Thanks for all the comments. The things I haven't gotten to understand yet are the oxidation and nitration numbers. Can someone please explain them to me?

Thanks....bgin
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Here is an email I saved on the subject, but I can't recall who it was that sent it to me (it was either Bob, Terry or MoleKule)

1. Oxidation - oxygen interrupts or attacks
the hydrocarbon bonds and breaks them up at high temperatures, turning
the molecules into sludge, varnish and
lacquer. Synths have stronger molecular bonds and better molecular
arrangements than do dinos, since synths were
engineered to do that. Hence the better oxidation resistance, wider
VII, and greater film strength.

2. Evaporation - when a material transitions
from its liquid phase to its vapor phase due to heat. In dino oils, you
have
molecules of all sizes; the lighter ones will
evaporate leaving behind the heavier ones, the heavier ones contributing
to
sludge. This is why your viscosity increases
in dinos when evaporation is high, and it also loses its lubricity. In
synths,
the molecules are consistently longer,
stronger chains that resist boiling off at high temperatures.

Both oxidation and evaporation are caused by
heat, and both can contribute to sludge, varnish, lacquer, and increased
viscosity. In full synth's, the stronger, more
consistent molecule is more resistant to heat, evaporation, and the
breaching of its film.


Nitration results from the heating of O, O2, N2, OH, and H in the
cylinder during combustion. The separate gasses mix
and when burned, form many resulting gasses
including NOx.

NOx generation is highest during: high
pressures, high temperatures, during crank angles between 10 and 40
degrees, and when the A/F ratio gets near
16:1, such as in lean-burn engines.

NOx gets into the oil via the blow-by gasses
during the power cycle when the cylinder pressure is highest and when
when the temp of the buring gasses is highest.

EGR valves and large overlap cams introduce
exhaust gas back into the cylinder to cool it down, reducing generation
of
NOx.

NOx creates peroxides that attack the oil and
increase oxidation as well..
 
Interesting stuff Bob A.

Thanks for that.

I've filed it away for future reference. This kind of thing is helpful for adding to our collective knowledge base!
 
Good questions, sebring01. I don't know that there are standards. I don't think Wear Check has any. I do know firsthand that higher sulfation, nitration, and oxidation numbers seem to be a trend with the use of Tribomaxx. The same effect occurred when I used it in my '95 Powerstroke.

I don't know what the long term effects might be. Short term, they didn't seem to affect the wear numbers much, if any, but I don't know about the prospects of potentially destructive deposits forming over time. I know that sodium is an additive in other products, but is it a good one for long term use? Etc., etc. ?????

These numbers may not be an issue shorter OCIs, say 5000 to 7000 miles. ????

I also know that the wear numbers are good enough to justify exploring the issue(s).

Bob A.
 
Bob,

Two questions for you...

1) Why did you change the oil filter after only 3,300 miles? Was it because of the head gasket replacement that was performed prior to this OCI?

2) If you reduce your OCI to 5,000 - 7,000 miles will you be running the same filter over the course of the OCI, or will you change it half way through?

Just curious, as I feel that either filter you've used should hold up just fine for 5,000 - 7,000 miles (IMHO).
 
Andy H.,

Yes to no. 1.
Yes to no. 2.

And I agree with you at no. 3. I do plan to use the Baldwin B-161 filter for the full OCI. It is oversize for my car, but has the same performance specs. as the stock filter which is made by Purolator.

The Purolator I used in the first 3300 miles was actually a Purolator Premium Plus, not the stock Subaru model.

Bob A.
 
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