You can create and use a bootable MemTest86 USB stick to test the RAM. If you use the older version 7.5 of Memtest86, then you can configure MemTest86 to run more than four test loops, however, testing that much memory will take a long time even for just a single loop. Sometimes you must allow the memory test to run for days before a failure may show up. You can use the downloaded Memtest86 .iso or .img file as a source for Etcher to make a bootable MemTest 86 USB stick.
Option Boot the MemTest86 USB stick and select the orange icon labeled "EFI". Once MemTest86 begins to run you can safely remove the MemTest86 USB stick if you want.
Like @etresoft mentions, then only useful diagnostic is one which actually reports a problem. Personally I would disable the "Hammer" test which I believe is test# 13 since that test can fail even with known good memory (it is testing for a vulnerability with the memory where you "hammer" the memory very quickly a nefarious app could possibly gain control of a computer). Since this specific test may fail even with otherwise good memory, I would disable it to focus on the other tests so maybe you can get more test loops in.
While the Kernel Panics seem to indicate a memory issue, the problem could be due to something else such as bad power supply or bad Logic Board. OWC memory should work fine in a Mac.
Maybe remove all the memory and install just the new OWC memory into the slots occupied by the original Apple memory. Sometimes third party memory just does not like working with other brands of memory (or sometimes even the same brand of memory made from a different time/location -- yes, some systems are that particular with memory).
