Just to update for everyone
The oil cooler failure may be due to a too high oil pressure.
In fact, we found the oil pump valve relief piston was stuck... being blocked by dozens of small particles from the oil pump gear. Looks like the GM racing hardened gear should be needed.
So well, that's a good occasion to have the external oil circuit redone.
The oil cooler will be simply removed as a first step as we are using a special oil tailored for very high peak temps.
Classic JIC-6 fittings will be welded on the OE adaptators
And of course, temp and pressure will be monitored like it should
