Quote:
Originally Posted by tCsonfrs
Why??
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I'll let my blog post do the talking:
More Fluid Changes and Blackstone Labs Oil Analysis
I racked up just shy of 10,000 miles since my last oil change over 6 months ago, which meant it was time to do it all over again. The timing worked out perfectly to allow me to change all of my fluids before the weather got cold enough to make it an annoying task. For those who haven’t been following along with my previous oil change posts, I use AMSOIL fluids in the engine, transmission, and differential. I also follow a modified service interval. For the transmission and differential, Subaru suggests a 30,000 mile oil change interval, but I dropped that to 20,000 because of my severe use, and because I think AMSOIL fluids are a bit thinner than the OEM fluid. The transmission and differential fluids looked fine when I changed them (though I assume the transmission fluid was changed when I had the throwout bearing replaced recently). Also, there were no more metal shavings on the magnetic drain plug for the differential than one might expect after 20,000 miles. So no issues there.
Subaru dictates a 6,000 mile oil change interval for the engine, but AMSOIL claims 25,000 miles, or 15,000 under “severe use.” Since I fall well within the severe use category, and didn’t want to push my luck, I’m doing 10,000 mile intervals, which is still significantly higher than what Subaru suggests. I’m also sending samples at each oil change to Blackstone Labs for analysis. Before we get to those results, though, let’s consider the past 10,000 miles: