I've seen the chart with the pictorial of how to judge whether your lamp is overheating.
What I'm curious about is the actual temperature your lamps run at?
To my wife's chagrin, I've got 7 lamps sitting on our dining table. 5 of which are Lava Lamp brand with their original contents and recommended bulbs. 4 of those are 20oz bottles with 25 watt bulbs and one is a 32 oz with 40 watt bulb.
Per my IR thermometer, the liquid in them all hover around 135 degrees when they've been on for a few hours.
Two of the lamps are filled with my own contents. One is a Lava Lamp 52 oz globe that had nasty faded contents so I refilled, the other is all DIY with a jar I bought at Hobby Lobby, it's probably slightly bigger than the 52 oz jar. Those both have 40 watt bulbs.
Both the homemade contents jars, when they get close to that 135 degree temp (or actually a little lower) really get to where the wax is floating at the top mostly. The Lava Lite version will eventually have the wax all form one blob at the top.
I'm wondering if adding more brake cleaner to the home brew lamps would help them flow better at the higher (closer to operating) temps? Will that also make the (already couple hour or so) warm up time?