I have a 2001 Subaru Forester and I use conventional oil. I’m looking to buy a new model (2015 or newer) - will I now need to use a synthetic oil?
If your Subaru is a 2011 or newer Forester, a 2012 or newer Impreza, or a 2013 or newer Outback, Legacy, Crosstrek, or BRZ, or Ascent - it is REQUIRED to use synthetic oil.
Yes. BTW - Worth reading before buying what you plan to.
For the 2018 Forester, from what I see both the turbo and non-turbo engine require the “SN” version of synthetic, but the two engine types use differing engine oil viscosities.