It is easy to change a Lava Lamp's light bulb. All you have to do is remove the globe and unscrew the light. Below is a list of the lights needed for each type of lamp.
Lava World
8oz Series 15 watt T7
20oz series 25 watt S11
32oz series 40 watt A15
52oz series 40 watt A15
Starship 40 watt S11 OR 40 watt R14 NOTE: Both lights make the lava look and flow differently so its up to whatever you like.
Wizard 40 watt S11
Wizard Glitter 40 watt S11
Blip 25 watt S11
Blip Glitter 25 watt S11
Mathmos
?
Motion Lamps
Hot Rock 40 watt R14
Peace 30 watt R39 NOTE:If the lamp has a dimmer get a 40 watt R14
Pliable Arts 40 watt S11
Student Lounge ?
Bomb/Torpedo 30 watt R39 NOTE:If the lamp has a dimmer get a 40 watt R14
Rocket 30 watt R39 NOTE:If the lamp has a dimmer get a 40 watt R14
Crayon ? NOTE:If the lamp has a dimmer get a 40 watt R14
Beaker 30 watt R39 NOTE:If the lamp has a dimmer get a 40 watt R14
Nova 40 watt A15