Making magic pyre logs and selling them for RS gold
The magic pyre logs are used in the Shades of Mort’ton mini-game, the Legacy of Seergaze quest or the Columbarium to cremate the remains of some certain monsters. The maximum limit of magic pyre logs that can be made is 2,500. This can be made possible by combining the four doses of sacred oil with magic logs. Although it is safe to assume that 2,400 magic pyre logs is more realistically possible to make. Through merchanting, you can make more RS gold by making magic pyre logs near the Grand Exchange and by buying both the sacred oil and the magic logs.
But only 1000 sacred oil can be bought on the Grand Exchange every 4 hours. The four doses of sacred oil is high demand in the Grand Exchange but the problem is due to low on supply. The only solution is to buy three doses of sacred oil and combined it with magic logs. But using the three doses will decrease the number of magic pyre logs you can make but you can still make a decent amount of RS gold using this method.