Strange: 0W-30 GC+LC+FP in G35, 4,800 mi (Particle Counts Too), ~15k mi on car

[Mickey_M]

quote:

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ekpolk:
.....Also, the particle counts generated an “ISO Cleanliness Code” of 15/12, per Blackstone, which is “considered clean for a used engine oil”. I was also told that this PC result would be considered acceptable for continued use in a hydraulic system. But honestly, I have no idea what this ISO score means, or how good it really is. I'd appreciate some help with that.

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I had to go look this up.

The SAE has in place some test procedures for oil filters, one of which - efficiency - uses AC fine dust in known percentages of particle size.

Apparently about 85% of hydraulic system wear problems are due to particulates.

Not too long ago the International Organization for Standardization (ISO) and the National Fluid Power Association (NFPA) revised their standard reference materials more or less analagous to AC fine dust. The current ones are:

ISO 12103-1, A4 Coarse (coarse test dust)

ISO 12103-1, A3 Medium (medium test dust)

ISO 12103-1, A2 Fine (fine test dust)

ISO 12103-1, A1 Fine (ultra fine test dust)

Testing procedures in the hydraulic industry appear to be somewhat simplified compared to motor vehicle methods. I assume this is in part due to the fact that the hydraulic fluid does not get contaminated with soot and other combustion byproducts that darken the oil and make optical measurement systems difficult to implement.

Here's a brief article on the use of the ISO 4406:1999 Standard and how the results are read:

http://www.pma-magazine.com/articles/2003/November/5

"Cleanliness targets remain the same. Lab test results reporting by ISO 4406:1999 Standard have changed. Instead of the old two-digit code (16/13), test results contain the new three-digit code (ISO 20/16/13), with the first set of digits reported value at 4.6 µm, the second digits reported at 6.4 µm, and the third set at 13.6 µm levels as shown in the table. "

 

[ekpolk]

Thanks to everyone for the interesting and useful info. I've reviewed it, and overall, I'm very happy with things. Wear is low-to-nonexistent, and the M1 oil filter has given me oil that's literally clean enough to use in a hydraulic system (these are very sensitive to particle contamination damage).

I remain puzzled, however, by the TBN on this oil. I did use a bottle of Redline S1 (fuel system cleaner), in 2 oz doses, during this interval, but other than that, I just don't see what would have made it go from 10-ish down to 3.8. I've seen some info to the effect that TBN decline is very non-linear, and I hope that's true, since I'm going for another 5k on this oil. Consider as a comparision point my wife's Sequoia's 4.7L V-8 -- same oil (GC) in for six months and 4,500 (about the same miles), same Lube Control, but with less FP, and we got a TBN of 6.0! Anyone got any thoughts about this?

 

[TooSlick]

There's no thickening from oxidation and the total solids level is very low @ 0.1%. An allowable limit would be 0.6% for most synthetic lubes.

I see no issues with running this oil for another 5000 miles. The Blackstone TBN's are very low - this is actually more like a 5.0-6.0 if you're correctly using the ASTM D-4739 method.

TS