Coolant on top of engine near oil cooler

[Htci]

Thanks Guys,

I'm looking at the following diagram for the o-ring part numbers and see more than two sets (total of four o-rings and that's likely due to the intermediate plate)... Also, after reading other posts related to oil cooler replacement I recall that some suggest an oil change. If I drain the coolant, bleed the coolant from cooler by removing breather tube, all of the coolant should leave the system so shouldn't I expect virtually no cross-contamination?

Please advise and thanks so much!