I have 3 Grande Lava lamps.
I replaced the bulbs with 130 volt R20 bulbs but found that the lava was not as lively as before. I did some research and found that the 130v has a thicker filament and burns cooler than 120v.
I am ordering some 120v and will verify my hypothesis.
Reporting that one should always use a 120v bulb in the Grande Lava. The flow improved and lamp is back to normal after using 130v for way too long.
While you will probably extend bulb life running a 130v/100w for a grande, the wattage drops a decent amount when running it at 120v for sure. Somewhere buried in threads here there were some calculations being made on wattage drop when running 130v bulbs in 120v appliances.