Yes. Switching to Subaru Synthetic 5W-30 Motor Oil doesn't require any special steps or engine preparation. In an emergency situation, you can mix the two types of oil. However, it is best to not mix them, and the oil should be changed once you are out of this emergency situation.
Can I use 5w20 instead of 0w20 Subaru?
There are no issues with running synthetic 5w20 in place of a 0w20 because the operational temperature (20 weight) will be the same. Just to clarify, Subaru allows for the usage of up to one quart of 5w30 to top off the oil level in the event of oil consumption.Jul 2, 2020
Does Subaru Legacy require synthetic oil?
Subaru Synthetic Motor 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.