Aluminum vs. Copper/Brass
Aluminum prevails as the most common material used for passenger car and light truck radiators today. Though you may think aluminum radiators are relatively new, the first ones were used way back in 1913 by Rolls Royce. Copper/brass has been the material of choice for most radiators until recently because of its superior ability to conduct heat (twice as good as aluminum), greater strength/corrosion resistance and lower cost.

It says that copper /brass cool better then aluminum ..
and that there going back to copper / brass radiator

Aluminum vs. Copper/Brass
Aluminum prevails as the most common material used for passenger car and light truck radiators today. Though you may think aluminum radiators are relatively new, the first ones were used way back in 1913 by Rolls Royce. Copper/brass has been the material of choice for most radiators until recently because of its superior ability to conduct heat (twice as good as aluminum), greater strength/corrosion resistance and lower cost.
In the 1960s General Motors introduced aluminum radiators on the Corvette as a means of reducing weight. A typical radiator that weighs 15 lbs. in copper/brass weighs only about five and a half pounds when made of aluminum. European auto makers began using some aluminum radiators in the 1970s, but use here was very limited until the 1980s when the push to improve fuel economy began to tip the scales in favor of aluminum because of its lighter weight.
Ford started what would soon become a full-scale transition to aluminum radiators with the Escort/Lynx and Tempo/Topaz. General Motors put aluminum radiators in its then-new front-wheel drive X-cars (Chevy Citation, Pontiac Phoenix, Olds Omega and Buick Skylark). Since then the use of aluminum has steadily grown. Today, Ford uses aluminum radiators in nearly all of its cars and light trucks. General Motors is also using mostly aluminum. Chrysler made the switch with the introduction of its LH-cars (Dodge Intrepid, Chrysler Concord and Eagle Vision), restyled Ram series trucks and latest minivan. Among the Japanese manufacturers, the use of aluminum has also been rapidly expanding with Nissan and Toyota leading the way.
In 1985, only about 24 percent of all new domestic and import vehicles were equipped with aluminum radiators. Today, that percentage is well above 90 percent.
Though copper/brass has been steadily losing ground, a new lightweight "no-flux" brazed copper/brass radiator design may reverse the trend. The International Copper Association has developed this new technology to win back the auto makers with several important advantages. Because copper/brass cools more efficiently than aluminum, a copper/brass radiator can be smaller to reduce weight and space. One new design with a "compact core" dubbed "Cu/Br II" has two rows of fins between tubes and thinner tube walls. The radiator is about 7 percent lighter and 15 percent smaller than an aluminum radiator of comparable cooling capacity.
The new brazing technology for joining the tubes uses a copper/nickel/tin/phosphorus alloy which provides a stronger connection and is more environmentally acceptable than soldering (which uses tin/lead solder). Brazing also means "solder bloom" (a type of corrosion that can form inside soldered copper/brass radiators) won't occur.
The inside and outside of the new brazed copper/brass radiator is electroplated to give it "unprecedented" corrosion resistance - which is an essential requirement for all radiators today. The radiator can also be easily repaired and recycled, the same as other copper/brass radiators (nearly all of which end up being recycled). Furthermore, the amount of energy needed to produce one ton of copper from copper ore is only about 40 percent of that needed to produce aluminum from its ore, so the overall energy picture for copper/brass is more favorable than that of aluminum.