Engine oil Kendall or AMSOIL

I run Amsoil 5w40 warmer temps and Ravenol 5w30 colder temps.

Stage 2+ 2016 wrx here, in my experience (with having run both full synthetic amzoil and motul) I can honestly say that while both are rated very good for the FA-20 I would lean toward the motul simply for responsiveness. The car just seems to respond better to that brand, 100% just off personal experience

You can't go wrong with the Amsoil XL. I run OE 5w30, which offers plenty of protection for a stock engine. Unless your tolerances and clearances have changed, there is no reason you need 5w40. Modern synthetics, especially ones designed for the extra heat of a turbo, are outstanding oils.

In the past I always swore by Amsoil or Mobile 1.

It looks like even with the mileage difference, Amsoil still outperformed in most categories. Pretty impressive.

I decided to make the switch to Amsoil Signature Series because I see people switch to it and report no oil loss.

I recently switched from Liqui Moly to Amsoil recently, my wife's Tiguan seems to run a little smoother and is noticeably quieter at idle with the 5-40 European car formula.

Amsoil is just an above average full synthetic oil. It's nothing magical. It has a higher than normal "Total Base Number", which is what allows it to go longer between changes without going acidic.

I use Amsoil 0w40 or Eneos 0w50 in mine. For sealing and shear resistance for metal to metal contact, thicker is better.

I run amsoil Signature 0w20.