Copper actually has better heat transfer than aluminum. Are preferred as heat-sinks over aluminum. The advantage of aluminum cores previously noted , aluminum is stronger can be stretched thinner creating larger tubes and more efficient heat transferring cores. When building a radiator heat transfer is more efficient when using thinner tubing.
Part of radiator cooling efficiency is when there is more air flow and the ambient air is cooler than pressurized coolant in the radiator. I kept the non-working A/C condenser installed, lowers air flow but helps to protect the radiator from rocks and debris.
If I were in a desert with high heat I would probably be looking for an aluminum radiator such as a Griffin and OE HD, Previously alums were used for high heat conditions such as racing applications.
I'm in generally cooler climate with from ~40 to over 150+ inches anual percip. (depending on which area you're in.) and using a CSF 3 core installed new several years ago. Hasn't produced any leaks. It appears somewhat cheaper than my standard duty OEM, but cools better.
On average, on-road, my coolant temps stay between 195 - 200 deg. F. In heavy ocean sand I'm staying at ~210 or less in normal heat conditions. Over 85 deg. F ambient air temps, coolant temps may go a little above 210. The sand isn't light or hard pack it's heavy loose drifting ocean beach sand, loose up to a few feet deep, where larger pickup trucks, some 4x4 have gotten stuck. Any non 4x4 vehicles normally become immediately stuck.
The CSF has worked good so far, perhaps an OEM HD alum. would work slightly better and last longer? While looking at radiator I considered a Griffin and OE HD alum. but could not find any specs for the OE. The Griffin was over $500.00 the OE HD was around ~$350.00 ... decided to save a few dollars. A copper/brass radiator potentially is easier, less expensive to repair both from a rad shop and while off-road.
To preserve the cooling system and coolant, more recently installed a bypass filter in the heater hose. The coolant stays much cleaner, doesn't require changing as often. Sometimes coolant rated for 3 to 5 years becomes bad within ~one year.
