Maintenance on cars
 

How often should the fuel filter be replaced? I couldn't find it anywhere.
Also how often should the clutch master cylender fluid be replaced?

I'd go with "never" on the fuel filter... unless the car is having problems.

I'd treat the hydraulic clutch system the same as the hydraulic brake system. Some say they should be flushed every couple years. That said, I've never really flushed em at all. Well, I did my motorcycle once because the fluid looked so dark. And if I have the brakes apart for other maintenance maybe I'll do a flush then, depending on how the fluid looks. Can't say that my lax schedule has caused me problems.

I'd go w/ what Frank said, w/ the exception of diesels that have water separation, since those filters can "fill up", and water is no good for a diesel injection pump.

^Jah, definitely, diesel fuel filters are another matter. They should be checked frequently.

Honda recommends replacing the fuel filter when the pressure goes down, that's really weird because we don't have a pressure gauge connected to it. I replaced my clutch master cylender 23,000 miles ago. My clutch master cylender was empty and the car wouldn't move so they replaced it. The fluid is already dark, I know when the fluid is new it's so easy to change gears, it moves in like butter.

If you are having a problem, like the clutch pedal feels "sticky" when operated, and the fluid appears moisture contaminated (dark instead of honey colored) then yes give a flush a try. It's the easiest and cheapest thing to do before moving on to ripping stuff apart.

As far as the Honda fuel filter/pressure thing, that requires hooking up a gauge made for that purpose. If the engine starts and runs good, it's probably OK.

For fuel filters it really depends on your vehicle. If you have an old old rig with a carb and a 20-30 year old gas tank then you might want to replace that filter when you do a tuneup. If its a newer vehicle that has a non-rusting tank (plastic etc) and a large screen on the pickup tube inside the tank then its pretty unlikely you'll need to replace the filter for a LONG time if ever. I replaced the filter on my 4runner when it hit 200,000 miles just in case that was part of a running problem I was having...it wasn't though.

Clutch fluid (brake fluid) should be replaced every couple of years other wise you get condensation in the system. When you get in a situation where your brakes get hot (not common for hypermilers obviously) then the water in the system will turn to steam which makes your brakes perform poorly (completely fail in really bad cases). Also, the condensation (water) in the system will start to rust your internal brake parts like the master/slave cylinder bores in both the clutch and brake system.
One other thing, that dark color is actually the rubber parts in your hydraulic system wearing.
I replace my clutch and brake fluid every two years.

I just went to the shop for an oil change and they told me the clutch fluid should be flushed every 30k miles. That sounds about right. Which will be 2 years since I replaced the clutch master cylender. I'll flush it out the next time I get an oil change and i'll just change the fuel filter when the car hits 200,000 miles. Thanks guys.

CanadianDriver: Auto Tech - Brake fluid is frequently neglected

Here's what seems to be a good article on the subject.

Not convinced I'll convert to bi-annual flushing tho'.

I don't really believe in wasting big money for a car that you may trade in tommorow or total the next day. But not changing some fluids or never checking under the hood could lead to some serious problems. I think it would be safe to say that brake fluid should be changed at least every 30k