Rubber o-ring for oil sump plug

[jay44]

Hi,

After doing an oil change, I overtightened the bolt and ruined the thread. Instead of tapping out s larger bolt and using a helicoil, I was wondering if using a rubber o-ring would make a proper seal opposed to a copper crush washer. I know you can't use PTFE on the thread because of how it frays on tightening/under heat, but you could wrap PTFE inside and outside of the actual rubber o-ring to create a tighter seal (like wrapping a bandage round someone's arm). Would that also be okay or would the hot oil also degrade the PTFE in that setup?

[jay44]

Decky_Q said:

Is it an aluminium sump? Threads are pretty easy stripped in these, but on the plus side they are also quite easy to tap or fit a coil into as the metal is so soft.

O ring won't work as crankcase is under pressure and if there's an easy outlet at the sump plug then the pressure will just push the oil out past your makeshift seal.

The thread isn't compromised, I just tightened it past the maximum (I don't know the correct way to say this), so the threads are there, there are just too many now which means there's not s tight seal.

Very interesting about the pressure. Didn't even consider that, thank you. I'm happy to buy the helicoil kit, I'm fine to get stuck in but nervous with new things with cars. I'm not sure about the material.. it's s BMW e82 (1 series coupe)