For the average person and their "close to stock" modifications (would maybe consider K04s in that category.. I am not talking about seriously modified (engine work, huge turbos, etc) to their car simply changing the coolant, upgrading the fan (which will help the radiator work better resulting in lower temps) - Vast offers an upgraded fan
http://vastperformance.com/shop/prod...products_id=52, also adding water and meth injection will help drastically lower intake temps which will translate into lower operating tempratures as well. Also upgrading the fan switch so it comes on more often at lower speeds will also help lower temps as well. Oil coolers work well but unless you exceeding power out put alot the stock one should suffice for awhile and might be considered wasted money to some.
OP - Since you already have an RS4 doing the regular maintenance will help but you might benefit most from an upgraded fan, and water and meth injection.. Only issue I see running huge FMIC's that block the cars radiator is over heating at lower speeds where air flow cant get past the intercooler to the radiator which causes over heating on hot days.. (all too common for those in the South East)
Hope that helped and I am sure more experienced people will chime in an offer their advice.
Cheers
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