Don't let 'em sit for 8 years with coolant in 'em.
(https://live.staticflickr.com/65535/49518076023_e4022b872f_o.jpg) (https://flic.kr/p/2irK5Pr) (https://live.staticflickr.com/65535/49518076088_d7d9cf5c54_o.jpg) (https://flic.kr/p/2irK5Qy)
If it's a runner, there's the coolant voltage test that will show the anti-corrosion effectiveness of your coolant:
https://www.familyhandyman.com/automotive/car-maintenance/coolant-testing-with-a-multimeter/