You may want to try a can of the engine flush from the dealer, they have it behind the parts counter. A blue can for about $19.00
196k, 5/20/12 new ej257 short block, 8/20/11 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
Engine Build - Click Here