Here's my 6mos/4820mi UOA on this same oil.
Here's my 3mos/2232mi UOA for M1 5W-40 that I used for my Auto-Rx rinse oil.
Here's my 14mos/8800mi UOA on M1 0W-40.
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I pulled this sample a little earlier than expected. I had planned to go 9k mi, but we were leaving for a 2k mi road trip the following weekend & I didn't want the oil in there that long. It turns out that was a good thing, 'cuz this sample came back with flags that told me something was wrong. Relatively speaking, viscosity was too high, TBN was too low, & oxidation, nitration & sulphur products were out of reportable range. Thinking I had received someone else's report by mistake, I asked the lab about the results. The lab manager provided this response:
This made me face the problem I'd been ignoring: that my temp gauge had been somewhat erratic over the past few months. It would show normal temp, then drop to cold for a while, then run normal again. When the lab gave me these comments, I immediately researched the gauge problem & discovered that the Engine Coolant Temperature Sender (ECTS) often fails with less than 60k mi of use. My favorite local Saab garage verified this common failure & said they always recommend replacing both the ECTS & thermostat every couple of years to avoid problems. Since it typically takes us 4 yrs to reach a 30k mi major service point, I figgerd that's a good time to routinely change these two parts. Since the ECTS is also the fan switch, it won't turn on the fan when it's not working. I think this may be part of the overheating problem. Another part may be when the engine is shut off & the bum ECTS doesn't continue to run the cooling system. I got the UOA this past Saturday & we were leaving for a 2k mi round trip to Phoenix in a week (tomorrow). I started asking questions on Monday & scrambled to get the parts replaced & the 3k-mi-old 5W-40 & filter changed.
Anyway, the UOA still showed how good this oil is, & why I'll always recommend its use in a Saab turbo. Compared to the 14mos/8,800mi UOA using M1 0W-40 (which is now GM/Saab's primary US oil recommendation for these engines), iron's only a hair more than 1/4 of what it was & lead's a hair less than 1/4 of what it was. Silicon's up a bit, but I think that may be related to my cleaning the K&N air filter. I pulled the filter out & planned to clean it, dry it & re-oil it over a weekend. In the meantime, I put back the 2 yr/20k mi old paper filter I took out 4 yrs ago. Things came up & I didn't get around to re-installing the K&N for a few weeks. On top of that, I think I under-oiled it. (This is the 1st time I've cleaned one of these things.) The only other oddity was that molybdenum jumped up.
Questions? Comments?
