Isx15 oil in coolant

[Kiko]

Hello all. I am having trouble with my Isx15 cm2350. I have oil in coolant. Trans cooler changed a year ago along with engine oil cooler. All was good untill lately and have oil in my coolant again. No pressure to n rad and no coolant in oil. Did a 20 psi pressure test on rad and after fixing some external leaks it will drop pressure after sitting. Removed oil filter and no coolant drops noticed. Removed turbo drain line and no coolant loss noticed. So a couple of questions. If it is engine oil cooler can I see coolant coming from it if I remove oil pan. Also has anyone seen a compressor create this problem without it pressurizing the rad. When running I am having no coolant loss from reservoir.