My understanding is that generally the EGR is only functioning at part throttle range. At idle, it can and in some cases does, cause stalling. At W.O.T. it kills performance. At those 2 extremes it should be closed. In between is when it's opening is metered.

How long ranger's has been loose is unknown, since it was loose when he bought it. So the combustion temps have not been fully reduced for who knows how long. Again, he probably been running hotter to some degree, and there's also the matter of hotter blowby gasses in the crankcase. Combine that with what Anita's tech friend said about defective EGR related engine failures. That's why I surmised that just for good measure, he should do a cheap oil change, if he hasn't done one recently.

I'm not saying that he has definite engine damage, just that since the duration of the loose and leaking EGR tube is unknown, an oil change is just sensible preventative maintenance.