Just got my results back from Blackstone Labs. Having a somewhat high mileage motor, my OCI's have been the ol' 3,000 miles/3 months, whichever comes first. Although, the most recent oil change was postponed quite a while. Before the recent oil change on the 9th of this month, I changed it back in February. According to my odometer, it only saw about 1,300 miles. Which could be a low estimate due to my speedometer not receiving a signal until about 25mph. It's probably a negligible difference though as I have driven at some slow speeds on the freeway quite a few times on my way to work. Probably not a low estimate by very much but I don't know for certain. Since buying the TDI, the truck has pretty well become a weekend warrior. I still drive it once or twice to work as well just to keep fluids running through it and the battery charged.

Anyhow, on to the results. According to Blackstone, my engine is in good shape. Wear metals seem to be at and on the right track to normal levels. However, they noted the high levels of silicon and sodium particles. I read recently on another discussion forum that sodium points to antifreeze. Is this correct? Silicon could be particles from the head gasket which I just replaced only 4 years ago. I've never had UOA run before, so could you guys shed some light on this and help me determine the results? I think my engine's paid its dues and is worthy enough for a rebuild. Especially if the silicon and sodium particles point to antifreeze and parts of the head gasket. Let me know if the picture is too small to read.



No oiled filter here. Been using a Fleetguard paper filter ever since I've owned it. I think it had a K&N in it when I got it but those particles have long since been flushed out, I'm sure. As with everything on the internet, don't believe all you hear/read. I found this article which breaks down the specific metals being examined and what they generally indicate if found in the used oil. http://www.bobistheoilguy.com/engine-oil-analysis/

Under silicone it describes:
"A very common contaminant most often found in a very abrasive solid form, which causes increased metal wear numbers (especially Iron) in oil samples. Its most common source is insufficient air filtration. However, in my oil analysis report it is actually harmless and due to leaching from a silicone sealant I used to seal a leaking valve cover gasket. Silicon concentrations in such cases as this will typically drop after each subsequent oil change."

Now, I have used RTV on the timing cover when installing a new crank seal. As well as a little bit on the seal of the billet tappet cover I installed. I was and am very conservative with it though. No RTV used in any other places that I can think of. I'm certain of that.

As for sodium:
"This is most commonly used as a corrosion inhibiter additive, and occasionally can indicate a coolant leak into the oil. Concentration levels vary greatly depending on oil brand."

I know this ONE sample after 400-500k miles doesn't quite reveal what exactly is going on but it's still a concern. I'll have to be patient and no so paranoid until I can send it another sample after the next change.