edyvw
$50 site donor 2026
Just because you are hot, doesn’t mean engine is.As I said, the manual recommendation is base on CAFE requirements. Ambient temps can affect recommended viscosity choices...if not for CAFE... and those alternatives could be included in the manual. However, CAFE language doesn't mean a passenger car operated in usual fashion will be damaged by the CAFE recommendation of a well-formulated 0w20 even in "hot temperatures". That said, I run Mobil 1 ESP 0w30 in three vehicles that spec 0w20 because I prefer using oil with a higher HTHS compared to the theoretical tiny increase in fuel efficiency of 0w20. Altitude affects viscosity choice even more-so than ambient temps due to less dense air providing less cooling effect at elevation...I'd be more concerned about using a higher viscosity during high mountain driving than with humid-and-warm Florida climates. Florida really isn't all that hot compared to the desert Southwest...and there are some high mountains out there as well. Florida climate is a walk-in-the-park in comparison.
Florida at 90 degrees is piece of cake compared to Eisenhower tunnel in Colorado at 40 degrees.
If someone is concerned about cooling, lowering coolant concentration is far more meaningful than running 5W40 which increases resistance and with that adds heat.