I would say that it is very important to keep your fluids clean by flushing them and watching their levels. But, of course, you probably knew I'd say that, so WHY? Well, spending a little time and money now will save you a LOT of time and money later.
Oils can break down with heat and moisture, which will make the components that need these fluids potentially wear out faster. Any time that you have a component failure, it not only can leave you stranded, but it can be very expensive to repair. Maintaining fluid levels and keeping the fluids changed at the proper specified intervals that the manufacturer gives you, will keep your vehicle and all of its components working properly.
If you take your vehicle to the same auto repair shop every time for your oil changes, many of them will keep tabs on your fluid levels and their cleanliness and let you know when it's time for them to be flushed. Otherwise, you can keep track of it yourself by recording it in a spreadsheet.
It is important to have fluids changed according to your maintenance schedule. Fluids break down over time and mileage and become less effective.
I always recommend that you have the system flushed instead of just drained so that all the old fluid is removed. I drive a vehicle with 297,000 miles on it and mostly that's because I follow my maintenance schedule and change my fluids to keep it running in peak condition.
〉 Answered on Mar 11th, 2011 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines