I have several 1960's and 70's cars in various stages of completion. Engines have been rebuilt, cooling systems totally flushed, etc. I was wondering if I should go to the newer HOAT, or the OAT, or perhaps a universal type coolant/antifreeze rather than putting in the older green technology. Once these cars are done I would like not to change the green coolant every two years that is why the other coolants appeal to me with their 5 year change intervals. None of the cars will be driven much, just to shows and to keep things lubricated. I would say hundreds of miles a year and not thousands. Any opinions would be welcome. Thanks