Oil filter sealing ring replacement

Hi, I need some advice about changing oil on a lexmoto assault 125.

I have the oil and most of the other bits I need, but I am having trouble with the sealing ring for the oil filter. The manual for the bike is not very good, but it says that the sealing ring should be replaced when oil is changed.

I want to change the oil asap, but until I take the filter off, I will not know what size ring I need for the replacement, can any give me any advice about this? Also can anyone tell me where the best place to get the rings are?

Thanks, grateful newbie.

Hi sealing ring should be in the box the oil filter came in, or do you mean the sump washer

Your bike doesn't have an oil filter as such , just a strainer gauze or " thimble" that you don't necessarily have to replace so there isn't going to be any sealing ring that comes with a filter. All you need to do is give it a blast of brake cleaner or wash it in a bit of petrol to get rid of anything that has been caught in the mesh . Although the manual may tell you to replace the sealing ring this is simply accepted workshop practice. In reality the ring which sits under the screw off cover will probably be good to re use many times before it needs replacement. As long as it isn't perished and it is still round in cross section it will be fine. Anyway, if you do feel the need to replace it it's 30mm diameter by 3mm thickness.https://m.ebay.co.uk/itm/30mm-x-3mm-Viton-75-O-Ring-Choose-Quantity-30x3-mm-New-Metric/292492925070?_mwBanner=1&_rdt=1 You might be able to get one in the odds and sods section at a good car parts shop or even Halfords.

Thanks for the help