balbrec2

From what I know, the design engineers at Subaru are a lot smarter than you or I. Stick with what they recommend.

I've never like to see oil come out of an engine looking new. It means its not working to keep deposits out of the engine. Even normal combustion by products should cause the oil to darken somewhat.

I have a 2015 Legacy 2.5 with 29k mi. and a 2015 Impreza 2.0. with 20k mi. Neither uses any measurable amount of oil between 6k oil changes. These cars are not babied yet not beat on either. Both broken in according to the owners manual recommendations. Guess we just got lucky!

Would be interested to hear the impact on fuel economy

Next? I don't think that far ahead with my cars. Haven't had the Legacy a year yet and since I tend to keep my cars a very long time, my next car isn't even on the long range radar. Very happy with this one in all regards.

Is there some documented evidence that this needs to be done in lieu of the service intervals in the maintenance manual? I just can't see spending the time or money on something that is not needed. To me this is like changing oil at 3K miles instead of the recommended 6K. Unless you have a proven need, why ??

Subaru says for the 2.5, 0W-20 synthetic every 6000 miles with a new filter. Use what ever flavor you like, keep all receipts. Or take to your Subaru dealer for maintenance. Stretching past this may be ok according to the oil manufacturer but since Subaru is who holds the warranty to your engine, the wise thing to do is follow their recommendations. After the warranty is expired , do as you see fit!

No way would I go that long on any oil! It may retain some of it's lubrication properties but oil gets dirty with use and TBN declines also. After a while it may lubricate but it can't do the rest of it's job. Have you ever sent a sample to the lab for UOA? I'd be curious.

has anyone looked into whether changing out the RSB would cause any issues with the new vehicle warranty?