sethroid

We bought our 2009 Q7 (SLine, 4.2L, gas) last February, and the first oil analysis prior to changing the oil showed evidence of coolant present; sodium and potassium. The two obvious culprits being oil cooler and head/block interface (crack or gasket). But at the extremely small amounts showing in the sample, (e.g. 90 PPM sodium), I'm not sure if it warrants any corrective action at this time.

I would appreciate any thoughts.

silveraudiS444

Hi - I have a 2014 Q5 TDI that I have had Blackstone Labs perform oil analysis from day one. This past oil change the report cam back similar to yours. I have 20k miles total. I sent Blackstone labs an email to followup and here is what they said. This helped a little bit, but I truely wonder, since they always end their analysis with "check back in xxx - xxx miles". I would be interested if you asked for additional information from Blackstone if they would send you a similar reply.

Hi, Mike. Thanks for the email.

As we said in the report, we're not completely sure that the sodium even is coolant at this point, so we're not ready to say whether it's a serious coolant leak. It's possible that this is something harmless; some types of oil use sodium as an additive, though there aren't any diesel oils that we know of that do. Depending on what type of oil this and where it came from, that could be the source. For example, if the oil came from a dealer bulk tank, sometimes we'll find that they've re-used a tank that had previously held a different type of oil, and the residual left behind may have some of the sodium additive. Or maybe a quart of something different was used at some point.

Of course, we can't be certain it's not coolant either, so in the interest of erring on the side of caution, that's why we suggested you keep an eye on it and not extend your oil change interval for now. If this turns out to be the beginning of a coolant leak, sodium will probably increase, and so will potassium; most types of coolant contain both of those elements. If this is coolant, 41 ppm isn't a lot -- maybe a few hundredths of a percent. As long as it's not causing excess wear or other problems, it's probably nothing you need to take action on yet, so we'll just see where things go from here next time. Hopefully, the sodium will go away on its own and we won't need to worry about coolant anymore.

Hope that helps. Let me know if there's anything else we can do for you. Thanks!

sethroid

Thanks for the info. I guess I won't worry about it too much until the number rise more quickly. I never detected any visible oil in the coolant either, but I guess at 90 parts per million it wouldn't be visible. It's still curious that these two elements do increase over time, indicating... something.

pchansen

I say this with greatest respect and as fellow gear head, but it seems like this might fall under the old adage of "if you look hard enough, you're bound to find something"
That being said, if I had a 2014 that was probably still under warranty, I'd at least send a copy of the report to my dealership and have them note it. If it's leased, well, I would lose a wink of sleep over this.