Here's a link to some UOAs (used oil analysis) from my 01 Pathfinder showing results from long interval changes (8K to 11K), it currently has 191K. The most recent results are on the left, 4 earlier tests to the right. The write-up for this last one is a little ominous, I'm going to change again at 4K and see how it looks. Anyone seen similar results? If it blows up anytime soon I may swap in a used motor and transmission, the rest of the truck is pristine otherwise. Running MaxLife 5/30 and Purolator PureOne filters for the last 100K+. If it's possible to re-post the test directly on this site, please feel free to do so, I couldn't figure it out.
https://docs.google.com/open?id=0BzpVMC ... ZhODViZGUw

EDIT by Towncivilian:

Here is the UOA in image form, click to enlarge:

Hmm... your values are pretty far off from the universal averages.

PureOne filters are pretty good, but maybe you should try running a conventional oil and see if you get more conventional results.

Interesting, thank you for the results.

Your silicon levels look fairly decent, but do a once-over of the intake plumbing to ensure there are no potential leaks. What air filter are you using?

Do be aware that the PureONE filters for our Nissans are rated at 99.9% at 40 microns instead of 20 microns. These filters are PL14610 and the smaller PL14612 (used where there is not enough room for the former), and their SAE-threaded equivalents.The reason for this is unknown. While I'm fairly confident that the efficiency at 20 microns is still respectable probably somewhere in the mid-90 percent range, this may impact your filter decision. PureONEs have excellent construction and plenty of media, but you may want to consider Bosch Distance+ filters since they contain thicker media than the PureONEs and thus have more capacity. I believe they have a thicker can as well, but other than that their construction and media is identical (and thus, I assume the Bosch D+ filters are also rated at 99.9% at 40 microns).

MaxLife is a synthetic blend oil (or are you running the synthetic version?). What made you pick this specific oil to run for such long intervals, instead of something more capable such as Castrol Syntec 0W-30 (termed "German Castrol" by some; it is a very shear-stable oil that produces excellent UOAs in general), Pennzoil Platinum or Ultra, or one of Mobil 1's offerings?

Also, your last two UOAs showed the oil thickening, no doubt due to the low TBN of the oil after such long (10k and 11k) intervals. I would not have chosen to run MaxLife so long; Valvoline's oils are generally not suitable for extended drains, in my opinion.

I'm no genius when it comes to UOAs, so I can't offer any insight regarding the rising trend of lead and iron, except to shorten your OCI by a couple thousand miles perhaps.

Thanks for sharing your UOAs!

I think the air filter has been a purolater or fram for most of the time I've owned it, nothing premium. I picked the PureOne oil filters as they seemed a good bang for the buck. The percent of insolubles in the samples never got above .4, so the filters seemed to be going the job. How do the Bosch Distance units price out? I chose the MaxLife (blend version, not full synthetic) as it was a well regarded oil, especially for the price, when I last researched it (several years ago now). Considering a TBN of 1 is indicates the oil is used up, the 10K and 11K intervals were definitely all this oil could handle (a few say don't go past 50% of the virgin tbn for the oil - in which case this was way past done). The tbn level at 8K was ok, so I pulled it at 8.5K this last time and didn't bother to pay the extra $10 for another tbn analysis. I wish I knew what "universal" average mileage the "universal average" was taken from to better compare. I'm going to pull it at 4K and see if the wear rates for iron and lead stay the same (i.e. half as much as the 8K change). Interestingly, this time the MaxLife had a lot less molybdenum - a wear reducer - than the previous samples. I don't know if this could contribute to the increased wear. Curious to see what the next sample says - sometime this spring.

The Bosch D+ filters are on the pricier side - about $11.50 each at Wal-Mart. They are easily capable of 15k OCIs, however. See one cut open here.

E-mail Blackstone to find out what exactly the "universal averages" refer to - I don't know myself, and am curious.

The reformulation of MaxLife to meet the recent API SN oil standards has lowered its molybdenum content, yes. Are you firmly entrenched with MaxLife, or would you consider running other oils? How much are you paying for 5qts of MaxLife?

The last time I bought the MaxLife it was $19 or so for 5 quarts. I'm definitely not set on it, and if the wear rates drop with the lower interval, I'll probably switch to a lower priced offering (maybe rotella 10-30w) or something, and keep the changes shorter.

Rotella is excellent; shear stable, high in detergency, and relatively cheap. Pennzoil Yellow Bottle is also excellent - see a virgin oil analysis here. You can see a several other VOAs of common name-brand conventional oils here too.

Remember that oil analyses aren't the whole picture. Not all additives get picked up in a typical $20 oil analysis - there are organic additives, after all.

Even "cheap" and, as some may claim, "watered down" oils, such as SuperTech (which is bottled by either Exxon-Mobil or Warren Performance Products, depending on region) provides good UOAs across the board. Any oil rated API SM or SN will do just fine for 5k OCIs at the very least, in my opinion.

Yeah the price of SuperTech is tough to beat. I've been getting the UOAs done mostly to track the health of the engine anyway, running the longer intervals was secondary. Hopefully I can get the wear rates back down somewhat, or at least see it coming if they keep going up.

The SuperTech filters are not awfully constructed either, but I wouldn't run them personally. The two ST filters that fit our Nissans do have metal end caps, but still have a relative lack of media, and they use nitrile anti-drainback valves which can become hard and brittle over time (see a SuperTech ST7317 cut open here). Also avoid Frams (except perhaps the XtendedGuard which are solidly built) - same deal as the SuperTech, but with fiber end caps, which seem flimsy in my opinion.

Wix/NAPA Gold, Purolator PureONE or Classic, Bosch Premium or Distance+, Motorcraft FL822 (basically a Purolator Classic clone) are all excellent choices in terms of filters. For 7.5k+ oil change intervals, stick with PureONE, NAPA Platinum (cut open here), Bosch D+, Fram XG, or Mobil 1/K&N (these two are identical save for the nut welded onto the K&N).

Lowering the interval to see where metals trend sounds like a good plan. Keep us updated!

Buck if you are already trying for extended drain intervals, then do some research on Amsoil. I know that thier Eao filters are top notch. They have been behind extended drain intervals since the 70's. The over all cost is higher but you need to realize that its good for 25,000 miles or 1 year (15,000 miles in severe driving conditions).

Amsoil does make great products, but you still can't blindly follow their 15k/25k oil change interval without at least a couple UOAs with TBN to verify the oil's condition, say at 12k and then 20k miles. And is the extended drain interval really worth the additional cost?

If you do UOA's through amsoil, you can go past their recomended intervals(if the oil hasn't dropped past allowable TBN). They will tell you when the TBN has dropped past the allowable limit and recomend you change the oil then. I may be biased because I sell Amsoil, but I also use it. The reason they can claim those change intervals is because the additive package in their oil is higher than most other oil manufactueres. Takes longer for the TBN to fall to a level that makes an oil change necesary.

I haven't done a UOA on my Q but maybe I should and post the difference from in the bottle TBN to one year use TBN. I have noticed that when I first put Amsoil in my q at 168,00km (milage when I purchased the truck) to now that color of the oil when I change it has gone from black to a nice amber color.

As for cost. If you calculate how often you should change your oil with conventional oil it works ot to 3000-5000k or every 3 months. Thats 4 changes a year. If its $30 for oil and filter (and thats the cheap side for conventional oil) then you are looking at $120 a year. An oil change with amsoils Signature Series oil and an EAO filter you are looking at around $80. Thats a huge savings and you go from conventional oil to synthetic. So it is cheaper to go with extended drain intervals and you have better protection for your engine.

One really must analyze their driving style and how much they drive. Constant short trips without allowing the oil to reach operating temperature to boil off moisture and fuel is not a prime candidate for extended drains.

I don't know what kind of "conventional" oil you're referring to, but a jug of Pennzoil Yellow Bottle and a Purolator PureONE filter can be had for about $19-20, not $30 as you say. And I never buy oil unless it's on sale - I bought 12 quarts of Mobil 1 for $36 a few months ago.

The difference in color from your initial use of Amsoil would seem to indicate that the first run cleaned out a lot of crud (given the oil's extremely dark color), and from then on just keeps things clean given its amber color upon draining.

I didn't read all the posts, as it looked a little too technical for me.
However, the first couple of sentences in your original post caught my attention: Intervals of between 8K to 11K. I presume this is miles, and not kilometers.
Personally, I think that's way too long, regardless of the oil or filters used.
I change my oil every 6,000-6,500 Kms, which is about 4,000 miles. Any longer than that, and I get a little antsy.
Try a few short interval oil changes, and then do you analysis again. It will probably clean up on it's own.
Cheers.

Maybe oil is cheaper in the US. I was using Castrols dino oil for comparison. Even if you choose to do less of an extended drain interval, Amsoil has their XL and OE line. XL is 10,000 miles or 6 moths and OE is at your manufactuer's recomended drain interval. Don't get me wrong I think if your are on top of changing your oil you are ahead of the game. I like Amsoil because I believe I'm putting the best oil made into my vehicle.

I look at it like this:
How many of today's vehicles are scrapped out due to an engine oil lubrication problem? Not many...
I run synthetic in anything turbo (so, my 240 and my Miata), but the Prelude gets the cheapest s*** on the shelf that week. Usually supertech (which as mentioned above, really isn't bad stuff). I then use either a supertech filter, or Pure one (and sometimes regular Purolator). Change intervals is around 4k, although the vehicle consumes roughly 2-3 quarts between changes at that point (changing the filter block seal this upcoming oil change, so hopefully that number will be reduced drastically).

My synthetic vehicles get pure one filters. I change the filter after about 3k, and change all the oil and filter around 6k.... sooner than that if I mess up the tune and end up getting some fuel in the oil.

PapaSmurf2k3 wrote:I look at it like this:
How many of today's vehicles are scrapped out due to an engine oil lubrication problem? Not many...
I run synthetic in anything turbo (so, my 240 and my Miata), but the Prelude gets the cheapest s*** on the shelf that week. Usually supertech (which as mentioned above, really isn't bad stuff). I then use either a supertech filter, or Pure one (and sometimes regular Purolator). Change intervals is around 4k, although the vehicle consumes roughly 2-3 quarts between changes at that point (changing the filter block seal this upcoming oil change, so hopefully that number will be reduced drastically).

My synthetic vehicles get pure one filters. I change the filter after about 3k, and change all the oil and filter around 6k.... sooner than that if I mess up the tune and end up getting some fuel in the oil.

I think you're changing the PureONE filters a little too often in the vehicles you run synthetic in, especially if you know that the engine's internals are clean. The PureONE filters are well built and can easily go 7,500 miles or more. Other than that, keep doing what you're doing, and the engine will outlive the rest of the car with ease.

UPDATED - It looks like the wear dropped significantly with the shorter interval this time(4500). I've switched to rotella and will change it again at 200K miles or so and retest. Wear is down a lot, but still not nearly the same as it was per mile when I ran 10K and 11K intervals about 30K miles ago. Truck still runs great.
https://docs.google.com/open?id=0BzpVMC ... 3diUWN0NEk

Looks like a nice report, glad to see that wear metals are trending lower. Thank you for posting your UOAs! I have cross-posted this UOA on Bob Is The Oil Guy here.