Both. My engine runs a little warm, particularly the
oil, which can be 15-20C above water temperature. I am working on fixes. In the meantime, I find that, in hot engine conditions (high ambient temperatures, stop and go, mostly go but not freeway, with high rpms between stops), turning the fan on manually, so it runs constantly, reduces my water temperature by 15-20C and my
oil temperature by 10-15C. I turn the manual fan on only after automatic fan has come on (and off) and temperatures are higher than I want. I have an SPF, two puller fans, fans are on in manual mode whether engine is on or off, hot or cold, so remember to flip switch to automatic or off when you shut car down to avoid battery drain (fan noise is a reminder).