I have seen a bunch. All caused by coolant. Same stuff as LSD and ULSD. Some, not all, of the components in the fuel systems of most OEM's had issues with the re design of fuel.
My shitbox was factory filled with DexCool. I had no issues with fuel or oil in the cooling system. Only symptom was a normal GM thing, running cool. Upon disassembly, nasty, swollen, gummy stat seals were found. Didn't want to just do the seals the first time, just did the stats and changed coolant. Stats fixed it, but did fill with a better coolant. I did the 1st WP somewhere between the 1st set of stats and the second. When I removed the oil cooler coolant supply pipe, the o-rings fell off the pipe and were all twisted. Again, no oil/fuel in the system, swollen from the coolant. Second set of stats and second WP, no issues with the rubber parts.
We did an experiment in the shop. Took coolant removed from a Volvo/ISX 15 before the directive to change coolant was issued. There was a big trucking company out here, KKW, that had something like 150 trucks with the "new" ISX, 2003 time frame? After half of the fleet failed with external coolant leaks and oil in the coolant, the Factory asked to put a few water grommets in the used red coolant and some of the Cummins stuff. Within a few days, the water grommets were swollen and nasty in the OEM Volvo coolant, as new in the blue stuff. Do not know what flavor they were using, it was red though. At this time, the 15l had multi piece head gaskets. Shortly after this test, we were instructed to install Cummins coolant in the trucks when repaired. The head gasket and oil cooler gasket failures stopped. Head gaskets for a bit, then the terrible multi piece design and liner fretting took over. Then oil cooler bundles!
I saw OAT/NOAT/ELC coolant first hand. The diesel industry was late getting into it as compared to the automotive industry. Saw the effect on the rubber components and, because of the issues, unfortunately, had to do a MESS of head gaskets and oil cooler gaskets in Volvo VNL chassis. They are NOT fun to work on. KW, Peterbilt, WS, etc had issues, but Volvo was flooding the market and that is when other OEM's market share took a nose dive. Those other chassis were much easier to work on! You should try working on a rear engine motorhome
I worked at an engine manufacturer factory distributor. Saw the failures first hand. Alot of them, across all of the platforms, A, B, C, k, QS series L, M, N and IS series, those in their infancy, as well as the re branded engines from China, Pakistan, India and I am sure more, that Cummins took under their wing, as well as older stuff that when serviced, the ELC was installed instead of "normal" coolant. It caused very extensive, expensive, warranty claims and non warrantable damage.