Looks like a load of fun!
The FDA recommends that if you want to make your own infused garlic oil, you should prepare it fresh and use it right away. If you are saving any leftovers, you must refrigerate it right away and use within a week.
From the University of Maine:
Best Home Method: Flavored or Infused Oils from Dried Spices
Using dried garlic and/or herbs is the safest way to make infused oils without acidifying the product. Fresh herbs introduce water into the oil, and dangerous bacteria need water to grow. Dried herbs and garlic add no water to the oil, so bacteria can’t grow.
Select a good-quality olive or other vegetable oil. Add your flavor additives to a clean container. Heat the oil to 180°F in a pot. Pour the oil over the dried additives, cap your container, and cool.
If you decide to flavor oil with fresh garlic, vegetables, or herbs, use a pH meter. Begin by selecting a good quality olive or other vegetable oil. Thoroughly wash and dry the fresh flavoring ingredients. Garlic should be finely chopped or crushed. Add the cleaned ingredients to a clean container.
Choose a vinegar with four to five percent acidity. In a pot, heat vinegar to near boiling (190°F). Pour the hot vinegar over the infusion ingredients, cover, and cool. Once the mixture has reached room temperature, add your oil and replace the cover.
You need enough vinegar so that the finished product has a pH of 4.6 or lower. This will keep C. bot from growing. Test the pH with a pH meter for food safety.
Although we do not advise making oil infusions with fresh additives at home, refrigerating this kind of oil infusion immediately after preparation will reduce your risk. Refrigeration will slow bacteria growth. Refrigeration will also slow the process by which oils go rancid. After one month, the number of bacteria in the product can become a food-safety hazard and it should be thrown away.
Acidified garlic, vegetables, and/or herbs in oil should be refrigerated. Do not store for more than one month. After one month, throw away any unused oil.