If pedals are not marked in, and there is nothing telling you that you can't use pedal, then I say use pedal. Pedaling is a constant adjustment of
1. How frequent you are changing the pedal
2. How deep you are holding the pedal down
3. How far up you allow the pedal to go up in order to clear it
4. How legato your fingers are
5. ALL OF THE ABOVE, always listen and make adjustments
1 is self explanatory,
2 and 3, some teachers will tell you there are 8 levels of pedaling, which means split the pedal into 8 levels of depth and use each level accordingly. Some teachers will tell you there are as many as 23 levels. There's a recording device however, which records not the sounds, but the depth, duration, speed of the keys being pressed, which recreates performances VERY accurately. The variable for the levels of pedal that can be used? something like 250+
What you should take from this is that the depth of the pedal is something you just have to listen for and adjust accordingly. Keep in mind that this varies from piano to piano (so does frequency of pedaling)
4. might be a new concept for you. Many pianists have the habit of holding notes down when they shouldn't be. If you clear the pedal, but are still holding the note, the note still sounds. You have to be careful of not letting any notes sustain any longer than you want it to sustain. However if there is a passage that cannot be played legato without the pedal, you have to be careful not to let the sound disappear for a sliver of a second.
5. LISTEN LISTEN LISTEN. Every piano is different, so you have to adjust on the spot, while constantly listening to the sound you are making.
There's also vibrato pedal, which is used to clear the sound more but still keep some sustain. Basically you just shake your foot on the pedal so that it semi-clears but the pedal still catches the note.