I finally did the oil change on my Sentra. It went a little longer than I intended, as a few long trips came up right when I was due to change it.
It looks like I actually have a slight antifreeze leak. I had hoped that it was due to bad filtration from the fertilizer blowing around so I had a new OEM filter for this sample. It must be very slight, as I have not had to add any coolant.
My check engine light also came on shortly after the first sample that showed potassium. I was going to replace the O2 sensors shortly, and maybe they will show some indication of antifreeze contanimation.
special low sulfur gas to reduce emissions. I do not drive particularly hard most of the time. The vehicle is used primairly for long distance commuting and long interstate trips.
Comments for at 56,126 by Blackstone Laboratories: John: Universal averages show typical wear metals for an oil from this type engine after a routine oil run. Your oil was in use 8,274 miles, far longer than the 3950 miles this is a routine oil run for the type, and we found all wear from the engine below average and in the correct balance to show normal mechanical parts inside. Air and oil filtration were functioning normally while this oil was in use. This was 10W/30 engine oil with no gas, moisture or anti-freeze in it. The oil was not run too long. The TBN was 8.5, a routine level for this type oil.
Comments for at 65,917 by Blackstone Laboratories: John: Very little change since the last sample. All wear read at or below averages, wihich is a very good indication of normal wearing parts. It is especially good considering this oil was run almost 10,000 miles and the average oil use is only 4,000. The only thing we found that may be a concern is the sodium and potassium. Mobil 1 doesn't use either, so they may show a trace of anti-freeze. It is not affecting wear, so we suggest just keeping an eye on it. The TBN was 9.5, which is higher then the 8.5 last sample. Suggest going 12,000 miles on the next oil.
Comments for at 76,946 by Blackstone Laboratories: JOHN: The fact that this oil was in use about 1200 more miles than the last, yet the Na and K levels remained the same, is encouraging. If your Nissan has a coolant problem, it's very slight and it's not getting worse at this point. Wear levels still look good, so we are not too concerned about the possible coolant. Silicon remained steady at 7 ppm, showing no problems at the air filtration/induction system. Insolubles were low at 0.2%, showing very good oil filtration and complete combustion. TBN read 10.5, showing plenty of active additive remaining.
Comments for at 88,399 by Blackstone Laboratories: JOHN: No new problems showed up in this sample. You ran the oil longer and this is the reason for the mild increase in iron wear. The other metals all still look great, showing no mechanical problems. Unfortunately, we are still seeing evidence of anti-freeze getting into the oil. Since this problem is not getting any worse, we don't think it is a major concern at this point. The TBN was strong at 5.5, so the oil still has plenty of active additive left. Insolubles were low at 0.2% showing good oil filtration. Try 13,000 on the next oil and resample to monitor coolant.
Comments for at 100,345 by Blackstone Laboratories: JOHN: Mobil 1 doesn't use potassium or sodium, so we think these elements fround in your last four samples are from a minor anti-freeze seep into the oil sump. Nothing has really changed a significant amount in this sample, even though you've added 500 miles to your oil use interval. Wear still reads normally with only iron wear above average, probably due to miles oil use and not the contaminant. If your bearing metals stay low, we think the contaminant more a matter of interest than a problem. The TBN was 5.3, still plenty high.
It looks like I actually have a slight antifreeze leak. I had hoped that it was due to bad filtration from the fertilizer blowing around so I had a new OEM filter for this sample. It must be very slight, as I have not had to add any coolant.
My check engine light also came on shortly after the first sample that showed potassium. I was going to replace the O2 sensors shortly, and maybe they will show some indication of antifreeze contanimation.
My comments: This is a California car, using the
special low sulfur gas to reduce emissions. I do not drive particularly hard most of the time. The vehicle is used primairly for long distance commuting and long interstate trips.
Comments for at 56,126 by Blackstone Laboratories: John: Universal averages show typical wear metals for an oil from this type engine after a routine oil run. Your oil was in use 8,274 miles, far longer than the 3950 miles this is a routine oil run for the type, and we found all wear from the engine below average and in the correct balance to show normal mechanical parts inside. Air and oil filtration were functioning normally while this oil was in use. This was 10W/30 engine oil with no gas, moisture or anti-freeze in it. The oil was not run too long. The TBN was 8.5, a routine level for this type oil.
Comments for at 65,917 by Blackstone Laboratories: John: Very little change since the last sample. All wear read at or below averages, wihich is a very good indication of normal wearing parts. It is especially good considering this oil was run almost 10,000 miles and the average oil use is only 4,000. The only thing we found that may be a concern is the sodium and potassium. Mobil 1 doesn't use either, so they may show a trace of anti-freeze. It is not affecting wear, so we suggest just keeping an eye on it. The TBN was 9.5, which is higher then the 8.5 last sample. Suggest going 12,000 miles on the next oil.
Comments for at 76,946 by Blackstone Laboratories: JOHN: The fact that this oil was in use about 1200 more miles than the last, yet the Na and K levels remained the same, is encouraging. If your Nissan has a coolant problem, it's very slight and it's not getting worse at this point. Wear levels still look good, so we are not too concerned about the possible coolant. Silicon remained steady at 7 ppm, showing no problems at the air filtration/induction system. Insolubles were low at 0.2%, showing very good oil filtration and complete combustion. TBN read 10.5, showing plenty of active additive remaining.
Comments for at 88,399 by Blackstone Laboratories: JOHN: No new problems showed up in this sample. You ran the oil longer and this is the reason for the mild increase in iron wear. The other metals all still look great, showing no mechanical problems. Unfortunately, we are still seeing evidence of anti-freeze getting into the oil. Since this problem is not getting any worse, we don't think it is a major concern at this point. The TBN was strong at 5.5, so the oil still has plenty of active additive left. Insolubles were low at 0.2% showing good oil filtration. Try 13,000 on the next oil and resample to monitor coolant.
Comments for at 100,345 by Blackstone Laboratories: JOHN: Mobil 1 doesn't use potassium or sodium, so we think these elements fround in your last four samples are from a minor anti-freeze seep into the oil sump. Nothing has really changed a significant amount in this sample, even though you've added 500 miles to your oil use interval. Wear still reads normally with only iron wear above average, probably due to miles oil use and not the contaminant. If your bearing metals stay low, we think the contaminant more a matter of interest than a problem. The TBN was 5.3, still plenty high.
