Just had 20k service on my 08 STi and surprised to see that the dealer has used 5w-30 oil instead of the usual 10w-40 (which they used for the 10k service)

Does anyone know why the dealer has done this?
Has there been some sort of technical bulletin from Subaru?

I'm concerned that this could be "a bit thin" for a turbo charged engine producing 300PS, but then I'm no expert!!

Would appreciate any info...

 

Technically it's the correct oil, the standard on which they are designed to run normally. As most people like to put their foot down a bit, I would go for a 5w-40