Roger Long
Senior Member
Blackstone was the oil analysis company I used when managing general aviation aircraft (where you really, really want to be sure your engine is OK) and they just reminded me why. I saw in a thread here (forgotten where) that they do not directly test for glycol in the oil so I decided to ask. It's this level of direct communication that sets them apart.
I just read on the Trawler Forum that Blackstone does not test directly for Glycol in the oil but infers it from the silicon readings. Is this correct? Previous CAT oil analysis by a yard working on our boat showed glycol in this engine. This has not shown up since I started oil analysis with you. I would like your thoughts on whether difference in methodology could account for this and why, if the forum post is true, you do not directly test for Glycol. The CAT report identified the coolant as being an immediate and critical concern and we had the engine flushed. That report is attached.
Thanks,
Roger Long
"Gypsy Star"
Roger,
The trawler forum is incorrect about the element we use to infer coolant from - silicon is not a reliable indicator of coolant content (some coolants contain silicon, some do not). Sodium and potassium are the indicators of coolant in oil.
Unfortunately, there is no "direct" test for coolant contamination, and it's presence/quantity is inferred using a couple of different methods. I don't know the specifics of the CAT test, but I would guess they use FTIR (Fourier Transform InfraRed) spectroscopy since they include nitration and oxidation numbers in their reports. That method estimates the presence/quantity of glycol by measuring the amount of infrared light absorbed by a sample in a specific wavelength range and compares it to a baseline of the virgin oil. The problem with that method is you need an accurate sample of the virgin oil to get highly accurate results.
We have and use a FTIR spec to test for soot in oil - it's good for that since that test does not require a virgin sample. We have considered using it for glycol, but prefer using the presence of potassium and sodium to infer the presence of coolant. Part of the reason is because FTIR is so good at detecting soot - soot increases the absorption of light across the entire spectrum, so it can introduce errors in the determination of coolant.
Based on the 08/2017 and 09/2017 potassium and sodium results on your CAT test, I think there was a decreasing amount of coolant in those two samples. Looking at our results shows no further signs of coolant contamination.
If you have any other questions, feel free to ask.
Ken Brandewie kenb@blackstone-labs.com
Blackstone Laboratories http://www.blackstone-labs.com/
416 E. Pettit Ave.
Fort Wayne, IN 46806
260-744-2380 Main Office & 416 Lab