Comments from Blackstone
4/1/07
This oil looks like it has about 3K miles on it and wear doesn't look bad. We found above average aluminum, which points to excess wear at the pistons, but all other wear looks good so we're not too concerned about it. Universal averages are based on an oil run of ~4,400 miles. No harmful contaminants were found and the air and oil filters (silicon and insolubles) are working well too. Nissan makes nicely wearing engines and we doubt yours is an exception. Check back in ~3,500 miles to monitor. If wear looks good then we'll suggest more miles.
7/5/07
This oil is still in use and aluminum from pistons increased slightly compared to the last sample. The universal averages for typical wear metals in oil from the 3.5L Nissan V-6 are based on 4400 miles of oil use. When looking at those averages you can see that aluminum reads 3 ppm, so there still is some excess piston wear occurring. No gas,water or anti-freeze was present in the sample and the oil's viscosity was normal so all of them can be ruled out as contributing to the high wear. We suggest changing this oil and its filter and try a 3000-mile oil run to help pistons.
12/10/07
The silicon has become a trend in the wrong direction. We can't say that is abrasive dirt because you are lengthening out you oil use intervals, giving a variable to the process. But if it is abrasive dirt getting past air filtration you could expect it to affect piston wear and the pistons are aluminum. We suggest taking a hard look at the air intake system on your Nissan to make sure nothing is awry there. All the other wear metals are steady and showing no signs of abrading parts. If you can get the silicon to average we will suggest 5,500 mile oil changes (comfortably).
5/19/08
We were looking for silicon to drop in this sample, and while it didn't drop, it didn't get any worse, either. That's encouraging. We recommended last time taking a hard look at the air intake system to make sure there are no problems there. If you did that and didn't find anything wrong, then we wouldn't worry too much about it. It's higher than it used to be, but still close to averages. Aluminum dropped by half, which is great. Other metals all look fine too. The TBN read 3.9, still active additive remaining. Add 2000 miles to this fill, then resample.
12/01/08
Wear generally increased here in your Nissan. Nothing read high enough to warrant alarm but we think we've found the limit that you can comfortably run your oil without it getting abrasive. We'd recommend 6,000-6,500 mile oil changes, unless the above-average aluminum (from pistons) doesn't bother you. Insolubles increased to 0.6%, which shows that your oil filter was overrun. The TBN read 4.4 so this oil still had plenty of life (active additive) left in it. 1.0 is too low. Aluminum really isn't too troubling, so if you want to leave this oil in place, it should be okay.
6/6/09
Silicon was the only element keeping this from being a perfect report. We have noticed it has been on a slow up trend for a while now. If this silicon was from dirt getting past the air filter, it would be causing higher wear, and it's not. We don't know where it's from, but it doesn't seem to be a problem. The TBN of 2.6 showed some active additive left. Insolubles improved to 0.4%, so the oil filter is still getting it done for you. If you're interested in running a longer oil change, go for 7500 miles next time. Iron will increase, but the other metals should stay steady.
