Springtime is a great time to check these fluids!

When to Change the Coolant?

Coolant is a blend of antifreeze and distilled water prevents corrosion, rust and scale buildup, plus helps transfer heat. It also keeps the liquid from freezing and prevents overheating.

But over time, all antifreeze breaks down. The pH balance of deteriorated coolant and the antifreeze depleted corrosion inhibitors become drastically more acidic over time which causes corrosion. Corrosion can ‘attack’ and damage the radiator, water pump, heater core as well as other cooling parts in the system.

Inorganic Acid Technology (IAT) needs frequent changes, typical every 2 years.

Organic Acid Technology (OAT) lasts much longer, generally 5-8 years as the maximum of 10 years.

Use pH strips to keep an eye on the system; deteriorated coolant must be entire flushed

If you’re in doubt about the ‘health’ of the coolant, completely flush the system.

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When to Change the Brake Fluid?

DOT 3 and DOT 4 brake fluids are hygroscopic, which means it attracts and absorbs water molecules from the surrounding atmosphere.

Once the corrosion inhibitor additives in the brake fluid are spent; moisture contamination leads to corrosion or ‘rusting’ of metal components. These compromised parts can begin to slough off some of their materials; especially the Fiero Rear Brake Calipers!

The manual says to change the brake / clutch fluid every 2 years.

DOT 3 and DOT 4 brake fluids are suitable for the Fiero brake systems: not DOT 5.

DOT 4 brake fluid offers better heat resistance than DOT 3, however DOT 4 absorbs moisture 20% faster than DOT 3

Since I drive in normal street conditions and DOT 3 brake fluid absorbs less water than DOT 4, I use DOT 3 in my Fiero.

Use pH strips to keep an eye on the fluid; deteriorated fluid must be entire flush and bleed out; especially the rear piston actuator {aka the parking brake mechanism}

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Phoenix Systems 8006-B Double-Ended Brake Fluid + Coolant Test Strips (15 foil wrapped test strips)



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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 03-08-2025).]

Good tips and post Like to add that coolant and brake fluid in a collector car driven say under 1000 miles per year should in theory last longer. As to how long I can't say. as a plus you can buy an inexpensive brake fluid tester that will detect any water in the brake fluid. I got mine for $3 on eBay.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 03-14-2025).]