I have several data points now on three labs:
Polaris (more expensive); Dyson Labs (more expensive); Blackstone Labs.

They are all fairly similar on the wear metals (w/ one exception discussed below), and close enough I suppose on the additive metals, etc.

The calcium, zinc, and phosphorous analysis (these are not wear metals) were off by a notable amount. One oddity was that in one set Blackstone was higher than Polaris but in the other set (the most recent set) it was reversed. They were within about 10% variability though. However in both of the two comparisons I did between Dyson and Blackstone, the Blackstone Zinc and Phosphorous were consistently lower than the Dyson results - between 10 to 20% lower. However, Blackstone's calcium was consistently 20% HIGHER than Dyson's. Interesting.

I will conclude at this point that it is probably a sampling issue or there is more variability in the test method for the calcium, zinc, and phosphorous. With these "additive metals", it is not hugely significant though (at least IMO). They are part of the oil formulation (additive packages). I do wonder if the Blackstone methods might tend to report these values lower than the other labs though.

Also in the comparison bewteen Dyson and Blackstone, the sodium levels reported by Blackstone were 2 to 3 times lower than what Dyson Labs reported. I realize the sodim levels are low (between 3 and 10 ppm), but the difference was consistent and "stood out". Sodium is considered a "contaminant metal".

Another thing that caught my attention is that the fuel dilution in the most recent oil sample from Blackstone came back at <0.5% and the Polaris came back at 2.9%. This seems to be a big difference. I certainly did not smell any diesel in the sample I sent. This is only one data point though.

In the comparison between Dyson and Balckstone, the iron levels were consistently low in the Blackstone analysis - by 50%. I did the Blackstone and Dyson comparison a few years ago when my iron levels were lower. Blackstone showed aboy 20 ppm where Dyson showed 30 ppm.

With the Blackstone and Polaris comparisons, the iron levels in both were consistent (82 and 86 ppm). For the Polaris sample, I immersed a VERY strong magnet in the oil before sending it to them. The iron is clearly not a magnetic form of iron. I am not going to do some investigation to see if the Biodiesel I use (B2) or the Stanadyne is contributing to the higher iron. It may make sense if the fuel dilution number is actually at the higher value!

Not sure what I can conclude of all of this. I guess I will say that for trending, I am quite happy w/ Blackstone. Their results seem to be consistent.

I guess if I had to choose which one was more accurate, I would pick Dyson.

 

Are you posting this info on BITOG? and if so, do you have a link?

 

I would find out the type of analysis equipment each lab is using before drawing any strong conclusions. The variation could be a simple issue of the threshold detection levels of the equipment. For example, one piece of equipment could detect particles down to 1 micron in size whereas another piece of equipment could only detect particles down to 2 microns in size. As a result, the total count will be different. I think the main thing is to use one source on a consistent basis. It's the trend you want to keep an eye on. As far as the fuel dilution differences, that's puzzling to me.

 

I hadn't posted on BITOG in quite awhile. I suppose I should do that w/ this info. I will update the link when I do.

Frank - I agree w/ the trend analysis. I was really looking close at the zinc and phosphorous levels in order to "consider" the ZDDP additive.

 

I have a question about your sampling method.

When you pulled your samples for each of the three labs did you run three separate sample bottles midstream from the oil pan or did you drain one large sample and then pour into three sample bottles?

FYI--I was doing some reading on BITOG a while back about "complaints" with Blackstones results being quite a bit different from other labs on certain products and thought it was strange. I suppose in a "real world test" it would be interesting to see the results from all three labs on the same vehicle with the same oil over a very long period of time just to compare the individual results although it would be very expensive just to "prove a point".

 

Midsteam samples drained into separate containers.

 

ok--I would suggest that next time you take a midstream sample drained into one container and divide THAT sample into three to see if the results are still different from each other. See what I'm getting at?

 

I agree. Like you pointed out earlier, I will probably only do one more comparison and then call it quits from a money standpoint!