See also:

Lubrication oil circulation in the refrigerant circuit
Operate the air conditioner compressor at a low engine speed (at idle or low driving speeds) a few minutes each month during the off-season to circulate its oil. ...

Winter driving
Winter driving ...

Rear differential gear oil
There is no rear differential gear oil level gauge. To check the rear differential gear oil level, we recommend that you consult your SUBARU dealer for inspection. ...