Change clutch fluid

[Stelcom66]

I saw an article on the doityourself website titled 'How Often Should Clutch Fluid be Changed?' Up until the vehicle I have now I haven't owned a manual transmission above 150k miles. I wonder how important/necessary changing the fluid is? I haven't read the whole article, but noted:

'The interval for changing clutch fluid will vary greatly between vehicles and drivers, along with environmental factors.'
'
'EXAMPLE: The author has a 23-year-old vehicle with 244,000 + miles on it and the fluid has never been checked or changed, but the clutch still works very well. '

I wonder if anyone has changed the clutch fluid and considers it part of an extended maintenance schedule? It's not something I planned to do. I'll wait until the clutch needs to be replaced. No signs of that yet.

[Rope-Pusher]

There are two types of Hydraulic Clutch release Fluid Reservoir Systems.

Going back to olden times, the hydraulic clutch release system would have it's own reservoir.

In these modern times we find ourselves living in, it is more likely that the fluid reservoir is shared with the hydraulic brake system. There is typically a port, somewhere above the bottom of the brake fluid reservoir, that feeds fluid to the hydraulic clutch release system. If the hydraulic clutch release system develops a leak, it cannotcompletely drain the reservoir, so the hydraulic brakes will still operate.

With either hydraulic clutch release reservoir system, the hydraulic clutch release slave cylinder might be external to the transmission bellhousing, acting on a lever which in turn actc on the clutch release (i.e. Throw-out) bearing, or it might be concentric with the input shaft of the transmission, located inside the transmission bellhousing, and directly acting upon the clutch release bearing. No matter where the slave cylinder is located, the opportunity to bleed the hydraulic clutch release system is most always located outside the bellhousing. This means that there is likely to be a greater volume of hydraulic fluid that is not replaced when one, or two, flushes their hydraulic clutch release system with a concentric slave cylinder.

Why would one, or two, want to flush / replace the fluid in their Hydraulic Clutch Release System? I'm thinking it would be to replace old and possibly contaminated fluid with fresh fluid - the same reason that hydraulic brake system lines are flushed. Heat can negatively affect the fluid, moisture might be absorbed into the fluid, lowering its boiling point and promoting corrosion of components of the hydraulic clutch release system. I also once read of an analysis of the hydraulic clutch relase fluid in a Chevy Corvette that was making some runs down a dragstrip. Some sort of contaminant was getting itno the fluid that looked like little black specks of matter - Dark Matter? - where are physicists when you need them? I was thinking it was clutch dust, particles of the clutch disk friction material. I was supposing that when a clutch pedal is rapidly released (side-stepped), there is a rapid reduction in the hydraulic pressure in the slave cylinder and it might be capable of drawing clutch dust particles past the seals and into the slave cylinder. Sometimes, seals are designed and evaluated for their ability to keep pressurized fluid in, which is not necessarily how well they function when the pressure inside becomes less than atmospheric. How harmful is contaminated hydraulic clutch release fluid? Is it only a problem if one, or two, side-steps the clutch?

I suppose that if it's easy enough to flush the clutch release system, at least in the section between the bleeder valve and the fluid reservoir, it may be worth doing at some time / mileage interval.

[Stelcom66]

You know your clutch systems! The article mentioned contaminants and moisture is a reason to change the fluid.

For over a day when try to access the forum section here I was getting an error that it was inaccessible. I don't recall exactly what it said.

[Rope-Pusher]

"PAY NO ATTENTION TO THAT MAN BEHIND THE CURTAIN!" was one of the error codes, if I remember correctly.

Yes, I don't think that I'm batting 500 when I attempt to view this site. Maybe the antenna was misdirected to point the wrong way:

Voyager 2: Nasa loses contact with probe after sending wrong command

https://www.bbc.com/news/world-66371569