I'm on the coast near Galveston, and right now I have seen a couple of days of 100 degrees and it looks like its going to hott for quite awhile. I have done mostly 5000 oil intervals with synthetics but b/c of this site believe I can get that out of conventional oils easily. I did try Amsoil 25,000 5w30 but felt it was too much of a stretch so chickened out at 12,500. No analysis but have concluded for peace of mind some shorter OCI's might help with cleaning after an extended run on oil.
As a side note I worked in an oil refinery for 32 years and saw the switch from conventional lubricants to synthetics and the effects longevity wise on rotating equipment by a factor of at least for. I imagine b/c of cost considerations for a barrel of synthetic oil many of the pumps received only filter change outs for extended periods or until a pump/compressor, etc. was changed out.