Is cleaning a neglected system a [censored] when it comes to causing leaks? I just changed coolant on a very neglected 96 Ford f150. It was so bad i didnt flush the system, just drained and refilled to avoid leaks. , I'd like to get the system clean, how would you handle it? Frequent changes? Filling system with distilled water and driving, draining and refilling? Flushing? Or just frequent changes? Or infrequent to not disturb the crud possibly sealing the system?