I would buy into everything said except Redline Waterwetter ... other than decreasing the ratio of coolant to water (increasing proportion of water), which increases the cooling ability since water is better than coolant at this part of the equation.
Would still like to see some independent tests ... a lot of folks have said its use lowered their operating temp ... sure, cause there is more water in the mix ... something independent would be really great.
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg