2001 Jetta 205,000 miles at sampling
Mobil 1 TDT 5W-40 CI-4+ (last of the CI-4+ that I have)
•
9957 miles (Sample # 2)
• Oil in sump for
314 days (5/24/09 thru 4/3/10) (Sample #1 from last year was in the sump for 308 days and was also Mobil 1 TDT CI-4+, so they make a great comparison)
_Total make-up oil added: 3/4 qt
_Fuel: ULSD + PS only, no bio for this run.
Side Note: Sample #1 had a TBN that was slightly low, especially for TDT. I speculated that if the WVO-derived B20 I had been using almost exclusively had not been properly titrated or acidified from storage problems, could have lead to my lower TBN on the assumption that combustion isn't perfect on these especially during cold starts. I switched back to Irving ULSD for this sample, and my TBN was up 55%, despite being identical oils in the sump for identical periods of time & miles. Interesting.
_Driving style: If it's driven enough to reach operating temperature, it will see WOT and at least 3,500.
_Synopsis of driving: These 10,000 miles included many short trips (7-10 miles) during the winter time after cold starts. I would say the miles were only about 50% highway, whereas the first sample was 75%.
_Wear rate: 2.81 ppm/1000 miles
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Nitration
comments? I think Polaris is over reacting a little, the TBN is good. They do mention that too much disparity between oxidation and nitration can indicate air to fuel ratio problems.
Viscosity is nearly unchanged from virgin (14.9) and soot is still low. I'm happy and don't see anything alarming.
Here's some gasser info on Nitrates (AFAIK I have a fully functioning EGR w/ stock setting):
[FONT=Verdana, Helvetica, sans-serif]
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.[/FONT]