How in the world do you check for proper coolant level on a C8 Z51? I Looked inside the cold reservoir and there is a stupid orange symbol with two arrows pointing at one another - what is that????? How do you know whether to add or not?? Never seen anything so dumb, except for me - not knowing how to add coolant if necessary

 

Add coolant a little amount at a time then drive until engine is hot and check again when engine is cool, you have to fill until tab is topped off by only a tiny amount, maybe 1/4 inch over that yellow tab. I've never see this on a car, and I've been driving since the 70s. It's a dumb system where you can't read the coolant level, visually, until the car is cold, because of all the plastics around the reservoir.

 

Interesting. I'll have to check this out myself.

Thanks for posting up and inquiring.

 

Huh? Your coolant gets colder as you drive?

 

Read the owners manual.

When the engine is cold, the coolant level should be at the COLD FILL indicator in the coolant surge tank. When the engine is hot, the level could be higher than the COLD FILL indicator. If the coolant is below the COLD FILL indicator when the engine is hot, there could be a leak in the cooling system.

 

Well your comment was kinda misleading. Thought you were referring to checking engine temps from console gauges.

I'm considering adding some Water Wetter to my coolant so this is of interest to me.

 

My comment was just read the owners manual. The rest was a cut and paste from my owners manual.

To me it means before you start your engine in the morning check the level.

 

Your reply seemed perfectly clear to me. Like every other modern car, the overflow tank has a cold fill line, so you check the level when the engine (coolant) is cold.

 

Speaking of coolant, is there a time/mileage when the entire coolant should be replaced?

 

Yes, it’s in your owners manual.

 

2020-2024 - 5 years or 150K miles, 2025 - 6 years or 150K miles.

 

Lots of really valuable info is contained in the owner's manual.

 

6 years, rather than 5 years, on a 2025 is debatable due to ambiguity in the owner's manual.

 

What is ambiguous about this statement?

Every 240 000 km (150,000 mi)
• Drain and fill engine cooling system. Or
every six years, whichever comes first.

It isn't just Corvette. All new GM vehicles have now moved to a 6 year life limit but still haven't caught up with other manufacturers. My 2024 Ram is every 10 years and I think Ford is the same. My wife's 2019 Avalon is 10 years and every 5 years thereafter.

 

Yeah, I can't find any ambiguous statement regarding the engine coolant replacement. Engine coolant replacement for the 2025 is six years. I searched for five and six and 5 and 6 year(s) and found no contradictory statement. But.......there is requirement to replace the "power electronic cooling system and rechargeable energy storage system coolant (E-Ray)" every 5 years. Perhaps that is the source of confusion. Eray has a separate cooling system for those.

 

Maybe they are confused with the differences between manuals for brake fluid replacement? In my 2020 owners manual it's clear in both Required Services and Severe Required Services.

In the 2025 it's different. No table, just text. In a highlighted section called Maintenance Schedule (in this section they say to check the level) then under bolded Additional required Services- Normal Service there is no mention. Then you have Severe Conditions Requiring More Frequent Maintenance then Additional Required Services (remember they have a section for this under normal) then Owner Checks and Services then five bullet points including every five years replace brake fluid. There's nothing there that says anything for 6 years, just 5, 7, Seasonal and Conditional.

Maybe? But I agree it's very clear on coolant.

 

Yes, in the 2025 manual, the Schedules Maintenance section starts on page 330 and under that is the sub-title "Additional Required Services –Normal Service". And under that subtitle are about 2 pages of text listing the milestones and service for each - ending on page 332 - with the 150,000 mile milestone. And that is the one that includes the six year requirement for coolant. Its followed by another subtitle for the "Additional Required Services –Severe Service". And interestingly, this is where we find the requirements to replace brake fluid (5 years) and also AC dessicant every 7 years - under "severe service". @RKCRLR was asking in another thread about the necessity of doing that. In the 2025 manual, its only required for Severe Service apparently (as written).

And to what I think is your point - its different in the 2020 manual that has the table form with footnotes. There we find that replacement of the brake fluid is every 5 years (vs six), but we also find that replacement of both brake fluid and AC desiccant (every 7 years) is required under the Normal Service schedule - whereas it only appears in the Severe Service section of the 2025 Owner's Manual. Its not confusing until one wonders: "did GM just make an error or did GM actually change the requirements from Normal to Severe only?"

 

Don't think one size fits all. Living in the desert we can see 115°. Flush my coolant at 3.5 yrs and never at a dealer.