My car (88 Accord) has a significant build up of rusty sludge and gunk. Even after a few normal flushes and one with a radiator cleaner product, the gunk remains.

Someone suggested using CLR to clear everything. Would this cause any damage to the various pipes, hoses, o-rings, gaskets, etc?

  • What, pray, is CLR? Is this something local to you?
    – Solar Mike
    Jan 30 '20 at 12:16
  • @SolarMike CLR is a cleaning product that is fairly common in the USA at least, at hardware stores, home centers, and other places where household cleaning products are sold. The letters stand for "Calcium, Lime, and Rust" which this product claims to help to clean. I don't think they market it for use in automotive applications and considering that the materials used in autos are quite different than those used in homes that it would NOT be a good choice.
    – jwh20
    Jan 30 '20 at 16:22
  • @SolarMike clrbrands.com/en-US/Products/CLR-Household/…
    – jwh20
    Jan 30 '20 at 16:23
  • CLR wont do anything for rust, its for things like mineral deposits.
    – Moab
    Feb 2 '20 at 1:41

No, CLR is NOT suitable for this use. From the CLR web site under the FAQs:

Can I use CLR to clean out my radiator?

CLR should not be used in or on a car radiator. CLR may not be compatible with the materials associated with a radiator and it could have adverse effects if the CLR is not rinsed out completely.

See: CLR Web Site

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