. . . 80/20. . ?
Not sure that you want 80/20. 60/40 might be better from the corrosion standpoint as Mike pointed out- catch22.
Currently have 60/40 and 1-1/2 cans WW. The car does what your car does; on the road it holds about 85C (w/ A/C going).
Going directly into stop-and-go traffic quickly raises the temp to 95C area. But that's where my fans cut in (based on temp) and it stays there maybe maxing at 98C. The fans may also come on sooner if the A/C pressure builds regardless of engine temp.
I don't think there's anything wrong other than the mixture ratio is a little low in AF. Remember 100C is only 212F which is boiling at atmospheric pressure. So with a 140 cap there sb no problem.
Regards . . . . JimF
'94 S500 Cpe
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