I tried that once. The owner told me that I ruined the cap and he had no intention of using only his hand to tighten it because the decal on the saw said to use the scrench. He demanded that I buy him a new cap. I did and he paid for it.I had one just today. I used epoxy to fill the slot and it is as good as new. Hand tightening is all that is needed on that saw. Echo cs 400 oil cap was lost and customer used a stihl one.