Slant six radiator fan too top hose clearance

Oh dang really? My car won’t heat up past 170 idling or on the freeway
Ya know, my slant also runs about 170* F. just cruising at 30-35 mph, but I think these temps are slightly below what is optimal engine/fuel efficiency. Could be thermostat isn't closing enough or too much coolant to water ratio? Maybe others can give their views on this.