I get 27-29 mpg in my '93 with the 180 tstat.

I think that the main engines that have benefited are the ones with the upper intake failure. It'* just proven by countless ones who have done it to work at saving the upper intake.

Ive been running 180 stats in everything. Ive got a 97 bonne with 125000 miles, original intake, trans,alternator,coils, everything but the water pump. Anyway, 195 stats were NOT introduced to keep oil from 'sludging'. they were introduced as an additional way to lean out engines in the search for "responsible energy managment'. Sludge was a problem with the 'road draft tube' technology simply because it was inefficent at best. The pcv systems are of course alot better but must be maintained. If anyone has major sludge activity going on, its their own damn fault. You cant blame it on any brand of oil, you cant blame it on reasonably lower temps. Change the oil, check pcv system often.

As far as temp swings are concerned, the swings are not a problem, only the RATE at which it swings. Cast iron is happy at any temp as long as it doesnt get there too fast...

I have a 180 stat and it helps a bit , but when driving in the city the car runs hot , thats just the way it was designed. keeping your rad fans on all the time is the key to a cooler engine,,,