SINGER W231 - Manual (Page 19)

òdtHtf
To see that your machine is always in smooth running condition
you must keep it oiled at all times. No grease is required. Just
a drop of oil is sufficient at each time of oiling. Points to be oiled
are illustrated in Fig. 28A & 28B. To oil your machine thoroughly,
it will be necessary for you to open arm cover and to turn the
machine over to get to parts underneath the bed.
After oiling, run the machine at high speed for a few minutes to
let the oil penetrate to all parts.
Fig. 2XA Fig. 2.SB