is any coolant dye good with Zerex G05?

Post by **JimBee** » 18 Oct 2025, 15:53

The following is from a Google (AI) search — the NAPA clerk insists they're all the same.

Google answer to the question above:
"No, it's not recommended to add any coolant dye to Zerex G-05, as the dye is irrelevant to the coolant's chemical performance. Zerex G-05 is a hybrid organic acid technology (HOAT) coolant that already contains a dye that can change color based on the system it's in. Adding another dye can interfere with the coolant's performance.

Dye color is misleading:
Coolant color is not an indicator of its chemical technology, and different technologies can have the same color. For example, Zerex G-05 is a HOAT coolant, while OAT coolants also exist."

So, I'm hesitating.

454cid · Post by **454cid** » 19 Oct 2025, 13:27

That sounds like AI is confused to the usage of the dye, to me. I'm not sure I've heard of dye for coolant, Though. If it's available, and I needed it, I wouldn't hesitate to put it in G05 unless the dye said not to.

I've never been in a situation where I thought a dye would do anything for me. If I have a leak, I either wait until it's big enough to easily see, or I use a pressure tester, and make it leak when cold, and look and listen for it.

Post by **JimBee** » 22 Oct 2025, 18:29

Today there was a puddle on the pavement where the car was parked for about half an hour. Looks like the water pump which is not too old really, with maybe around 40k miles. Gotta get the wheel off and have a closer look.

I emailed the support line at Valvoline that owns Zerex G05, got no response. The chat line at least responded but the person said there are too many products to keep track of so they don't suggest any. Not helpful—but the lead does look like the wp so I won't need the dye anyway, but still it would be good to know.