Heat Exchanger delete+oil cooler added

[Gelbster]

Thanks for chiming in JFP.
The leaking 'O' rings were supplied by Parts Container as part of a kit. The replacements are from Pelican .When I removed the heat exchanger the bolts were tight and the seals looked perfect. Dimensionally they are suspect and they 'feel' different(durometer?) from the new Pelican parts. The engine has zero miles - just test run.
After I position the new Pelican 'O' rings on the engine ,I'll use a straight edge and feeler gauges to measure how proud they are of the mating face of the crankcase. Odd that the stock spec calls for 4mm thick coolant rings but thinner 3mm oil rings. I suspect the measuring is irrelevant. Durometer is probably the issue which is difficult to test empirically diy. And then there is the material choice-HNBR,Viton.Buna(I hope not!). Hence buying from Pelican and trusting them.I presume it is verboten to use any sealer?
Here are the part numbers for the convenience of others.
999-707-389-40
999-707-409-40