Thursday, April 12, 2007
Oil Analysis Results
Just as the vendor (BlackStone Labs) promised, they emailed me a copy of the report in advance of receipt of the paper copy. The results are pretty self explanatory and indicate that the engine is running like a top at 142K miles. All the wear metals are well within reason and the oil reportedly contained no coolant, so I'd say it's good to go.
I find it interesting that the analyst pointed out that the viscosity of the BMW 5W-30 oil is slightly high for a 30W oil. And that's because it's supposed to be. When oils are classified as a 30 weight, that actually refers to a range of viscosities, and BMW 5W-30 synthetic oil is known to be at the high end of the 30 weight range. In this way it behaves more like a light 40 weight oil than a 30 weight and it is this quality that allows it to meet BMW's own LL-01 specification. That's why you can't necessarily use any generic 5W-30 oil and expect the same results. Lighter oils are known, for example, to cause the vanos to chatter as well as other top-end noise. While I think BMW 5W-30 is a great oil at a great price, if you're hell bent on finding something cheaper, just make sure you buy something that's LL-01 approved. For reference, Mobil 0W-40 meets the LL-01 specification but its 5W-30 does not.
The TBN value doesn't surprise me. There's a reason why BMW thinks it can get away with 15K oil changes. The oil may reach the minimum TBN just as the oil reaches 15K miles in service. But of course oil serves many purposes and the TBN number does not indicate the oil's ability to hold particulates in suspension, for example. Keep your oil in service until the TBN number says it's finished and it's likely that oil has already contributed to a build-up of sludge in the engine.
The fact that there was no water found (or at least it was below their measurable threshold) is likely because I drive it every day, at highway speeds, and get it up to normal operating temperature sufficient to burn off any water that may find its way into the oil due to the normal process of combustion or via a form of condensate. This explains one of the reasons why cars that drive short distances actually need their oil changed more often than those run at highway speeds every day.
All in all, I think the analysis was worth it. I'm not sure if I'm going to do the analysis at every oil change (something tells me I'll do it every other change just to develop a trend), but I do know that I won't bother with the TBN test again unless I change oil brands (very unlikely) as the results prove the BMW 5W-30 oil holds up well in my application.
If you have any questions about oil analysis, check out the BlackStone Laboratories site.