A slight leak of the crush washers.
Stop the by dealership and tell the parts guy you want two of the crush washers for it so they can be replaced.
Have your guy do next time.
215,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
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