Side marker lights

I replaced one of the bulbs on the side marker lights of out Worcester today with a 5w bulb.  I checked it at dusk and it is much brighter than the others, so clearly the correct bulb is a lower wattage.  Can anhyone tell me what the correct wattage is, please?  I also wonder if these very low wattages are readily available at the local motorists' stores, and if not, where can they be bought?

Are they not 5w amber bulbs? Use a white one and it will be brighter.

The one I took out was blackened inside - I presumed that this was a result of the bulb burning out.  Is that what you would call an 'amber' bulb, or is it like a normal indicator bulb?

Edit - spelling

Check the bulb in one of the other lights.

Amber

Thanks for the replies - I'll look out for those amber bulbs

I have just checked the bulb in my marker lights. W5W white not amber.

Thanks for that.  Yesterday was a long day out, so didn't have a chance to check.