Try checking "Cooking Oil" in the yellow pages (Commercial Industrial) then start calling the companies. Some will refer you to their bigger distributors form whom you can source your wholesale size cans.
Repacking is good business because the profit is in "tingi":
Example: sell one kilo of product with 20%margin
vs. sell 10 pcs of 100grams (1 kilo divided by twelve) with X amount of profit.
You get much much more than the 20% if you sell the one kilo only.
Tip: go to the nearest wetmarket and have small talk with the vendors/owners (of cooking oil) and ask questions.