I had an oil analysis done on my 300CD, almost exactly one year since the last time I had this done. I went just over 6400 miles in one year on the same oil (Shell Rotilla 5w30 synthetic; Mann filter).

The results of the analysis were surprising - more iron in the oil this time, but the lead and other heavy metal levels went down somewhat compared to before, when I tested oil that was only used for about 3000 miles.

I did the optional "TBN" test both times to see how the oil additives held up. They say the higher the number (scale of 1-10, if I recall correctly), the more additive is left in the oil. I got a 9 last time, and this time with twice the miles it was a 7.6. Anything that high is still serviceable oil, at least in terms of additives.

I asked a technician at Blackstone what this meant, and she said the oil is still good, but of course with more use of the same oil, there are more abrasive particles in the oil, so keeping it in longer is a trade off. She also said that regardless of filter brands, none of them can effectively filter out microscopic particles of lead, calcium, iron, etc., and that there was a lot of hype promoted by oil filter and oil manufacturers generally.

I'm not sure what to make of her dismissal of oil filter manufacturer claims, or about different brands of oil. I'm also weighing the benefits of more frequent oil changes versus slightly fewer (not sure how often the original owner changed the oil during the first 170k of car life).

Thoughts?

__________________
Gil

2004 ML350
1984 300CD; Ivory (sold)

FYI - TBN (total base number) is only testing reserve alkalinity. It is not a generic test for "additives" in a general sense.

Just wanted to clarify that, in case anyone was misled.


Tim

__________________
2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss)

1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss)

I generally agree that the filters are minimally useful in a well broken-in and good running engine. There isn't a whole lot of stuff being thrown off that will be caught in our filters. If there is, we have big problems.

Did she really mention calcium? Our oil comes with 2000 to 3000ppm calcium in it.

Can you post your results here?


Tim

__________________
2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss)

1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss)

I can't copy and paste from the report without losing the format and making a confused mess, but I'll post the numbers:


===============================
ALUMINIUM: 8 8 7
CHROMIUM: 4 4 3
IRON: 91 86 80
COPPER: 3 3 3
LEAD: 8 15 21
TIN: 0 0 0
MOLYBDENUM: 20 16 12
NICKEL: 3 3 3
MANGANESE: 1 1 0
SILVER: 0 0 0
TITANIUM: 0 0 0
POTASSIUM: 8 12 15
BORON: 3 2 0
SILICON: 8 8 8
SODIUM: 5 4 3
CALCIUM: 2952 3406 3860
MAGNESIUM: 12 16 19
PHOSPHORUS: 1099 1171 1243
ZINC: 1302 1383 1464
BARIUM: 1 1 1

The first number in each series is from last year and 3000 miles of use on the oil.
The middle number is for unit averages. I have no idea how they arrive at these numbers, nor do I know how often they've tested oil from this type of engine. The last number is the most recent result, with 6400 miles on the oil.

PS: The numbers indicate PPM (Parts Per Million).

__________________
Gil

2004 ML350
1984 300CD; Ivory (sold)

I find it interesting the lead and iron is up. Also up in comparison to the average. Is the oil a little too thin for the bearings and cylinder walls? Or are these numbers still generally okay?
Could it be just the same amount of normal bearing wear extrapolated over twice the milage as well plus almost half again. Yet most other things are not really up at all.
Thanks for posting your results of the oil test. Provides knowledge and food for thought.
I suspect if this is the first time synthetic has been used it might account for some of the increases and may not be reflected in the next test. No I do not think the sky is falling just interested.

FWIW, you can post PDF documents here. At least, I think that's how I posted mine before.

This wasn't the first time synthetic was used; I'd been using it for about two years before I had the first analysis done. The tech also thought there was little benefit to using synthetic (I disagree and pointed out that cold weather starts are much easier with the synthetic version of the same oil).

__________________
Gil

2004 ML350
1984 300CD; Ivory (sold)