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RX400H need help identifying this paste/gunk on radiator cap

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Old Jul 4, 2025 | 02:16 PM
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Default RX400H need help identifying this paste/gunk on radiator cap
can someone please identify this paste like material on the neck openning of radiator? what to do? Thanks

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Old Jul 4, 2025 | 04:03 PM
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Could be stop leak or simply old/low quality coolant. Good news is using Toyota Super Long Life will completely eliminate any issues assuming your cooling system is flowing properly, which it likely is.
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Old Jul 5, 2025 | 09:51 AM
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Looks like old coolant gunk.
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Old Jul 5, 2025 | 11:39 AM
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Looks like the precipitation from mixing IAT and OAT coolants. It's best not to mix IAT, OAT and/or HOAT coolants.



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Old Jul 6, 2025 | 12:25 PM
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Flush the whole coolant system & use red Toyota coolant........Basic mantenance. While your there, How many miles on the t/b, w/p?
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Old Jul 14, 2025 | 03:21 PM
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no idea T/B or W/P bought it used at 168000 miles.
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