Be careful with preserving in oil. You can get bad toxins after just a few weeks. Best way is to fry them in hot oil to kill off any bacteria before stroring in cold oil. Some people boil them in vinegar beforehand but I think that completely spoils the taste. Some also only preserve dried chillis to reduce the risk of fungal infections!
My advice is cook with them and freeze down the dishes. The meat marinates in the chilli as it freezes / thaws and is delishhhhh!