I am not saying that 180-190F is a hard limit. Yes even dino oil can withstand higher than that. Synthetic cand withstand higher than that. I am suggesting it would be an optimum max continuous temp as to really help cool the engine and take some of the load off the coolant. Also would help keep the piston a bit cooler and help keep it from swelling then gualling under heavy load.

I have never seen a GM spec for max oil temp. And it varies depending on the sources I have read for oil limits.

I have read Kubota's application guide for thier small IDI diesels and they state 248F for continuous and 266F intermittent as limits not to be exceeded. That is measured as "avg" oil temp in middle of oil pan. Its not the only indicator of engine load but it is a hard limit and if you can't keep oil temp below the above specs then they don't approve the application for warranty claims. ie if you run it hot and guall a piston (one the first things that happen for them if run hot) they don't fix it for free.

Now intermittent is rarely clearly defined for these type specs and depends on actual item. Its sometimes stated as duty cycle based on continuos time. Intermittent isn't very long usually and really more a possible high max limit that marketing keys on to show high numbers.

I'd say the oil temps you posted are a bit too high for optimum oil life for dino oil. You are fine because the other key temps limits are in check. Key indicators of load and application EGT, ECT, IAT, oil temp, engine compartment temps. You are generally ok if one is high but its not good for 2 to be out of range if 3 get out of range it leads to trouble 4 would cause damage more than likely (depending on how far over limits).

If you look at maintenance schedules for heavy towing or severe duty they recommend shorter intervals. I think just one of the reasons is due to this higher avg oil temps. Other reasons could be heavy use means more fuel burned and thus more soot and higher temps and more fuel combusted mean other contaminates that dilute additive packages.