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......... I know there is a reusable filter but i am afraid maybe the thread is damaged inside so.. what to do leave it like this. This is not cause engine failure??
https://ibb.co/zVgH2DdB
I have no knowledge about Downtown models but you are correct - if the thread is damaged at the inside and you manage to remove that nut you will probably face a bigger problem.
I assume the Downtown models have onother drain plug like the other models and you always use the other plug to drain the oil during oil changes.
I never found any dirt stuck at my scooters' screen filters and I've never seen any comments from anyone who ever found any dirt at those filters.
The purpose of the screen filters is to prevent any bigger pieces of engine components getting sucked into the oil pump - causing damage to the oil pump. Any bigger pieces of engine material will be sitting at the outside of the filter mesh (between the bolt and the mesh).
If you use another bolt to drain oil during oil changes I would not worry about removing the damaged bolt and I would rather not try to remove it.
Instead of trying to remove that bolt I would rather drain the oil by removing the other drain plug (if the scooter has another drain plug), put the drain plug back in place, and use Kreosene instead of oil to fill up again. DO NOT START THE ENGINE - just "shake" the scooter a couple of times to the left and right. The kreosene should "wash" off the dirt (if any) from the filter mesh.
Then remove the other drain plug again, and drain the kreosene properly. Just make sure there is no kreosene left in the engine.
Then put the plug back in place again, and and fill up with engine oil.
I have done this in the past to my first Agility when I've had problems with the original nut at the mesh filter. I've ordered a new nut afterwards.