Interesting discovery today. I discovered that my coolant reservoir on my 2006 are 53 JCW was leaking. I was prepared to purchase a brand new OEM replacement, because I personally feel that OEM replacement parts are higher in quality than aftermarket parts. A lack of availability forced me to purchase an alternative to OEM. To that end, I ended up going with a company that has historically produced fairly good replacment mechanical parts, Dorman.

Of course I would never in a million years purchase the electronic part from the Dorman under any conditions!

I unboxed the new part, and low and behold, it is identical to OEM, right down to the MINI logo on the bottle, and the OEM part number on the bottom of the pressure cap.

Just FYI. Cost of replacement part was the last and a half.

Just for the record, my vehicle uses a pressurized cooling system.

 

I too found with certain plastic parts that the OEM ones fail, Dorman can be excellent alternative. Yes. It must be a Chinese company. I think they make a point to cash in in the niche products to fill need for parts with high replacement rate.

 

When that new plastic OEM tank starts leaking, which it will, replace it with one of stainless steel and forget it. Lots of guys are going with them.

 

Keep an eye on it. We have found the replacement plastic tanks to be no better and usually worse than the originals. So much so we won't even put a plastic tank on a customer car here in the shop as we can't afford the comeback when it fails.
I'd only recommend going with an aluminum tank with no seem to fail.
https://www.waymotorworks.com/polish...-tank-r53.html