In the next month or two I'm probably going to be reaching 120K miles on my 2012 3.6R. I see there's many things that need service that I know will take longer than the usual (brake fluid, spark plugs, fuel filter, likely differential oil, plus standard oil/filter/check everything) than at most service intervals and "looking ahead" coolant is due at 137K.
I'm wondering if there is any benefit or detriment (other than to my bank account) to just replacing the coolant at 120K with everything else and have them work on everything with this "takes all day" big work so it's done with at once and I don't have a long all-day service AGAIN in 13.5K miles too?
I'm also confused what happens when I replace the coolant, I see some places say it's another 137K, online manual for my car references 75K for the 2nd replacement (but no 3rd?), and forums and shops/dealers range from 30/60K to 120-130K claims. I'm trying to think "long term" because I really want this car to last "forever", so I am trying to plan stuff out reasonably well; I average 400 miles/wk just to and from work.
I think the "Subaru Blue" coolant sounds like a good idea from what I've read on here (vs the "regular all brands" green the local shop would use by default) but I want to understand what I'm doing before I make commitments.