Lots of guys use them without “problems”. But they are more catered to the drag crowd. I prefer the extra cooling myself. I always use a new oil cooler, but, I have cleaned a couple of them as well. I pour gas in, cover the holes, shake it violently and dump it, and then repeat that about 30 times lol! Then the last few times I use brake cleaner. By the time I’m done there isn’t a spec of aluminum coming out that I can see. Yes a new one is the way to go, but like you said, they are on backorder and there really isn’t another option. You could even try bringing it to a radiator shop and have them clean and flush it out.