Quick answer
RV antifreeze is non-toxic plumbing antifreeze (usually pink) for water lines, traps and tanks, not engines. It's typically propylene glycol and/or ethanol based (check the label). To winterize: drain the water system, bypass the water heater, then pump RV antifreeze through each faucet until it runs pink, and pour some into the drains. Never put it in an engine, or engine coolant in water lines.
Confirm the manual or equipment specification before buying.
What to buy
Start with the genuine coolant your car maker sells, if your owner's manual calls for it.
Have a spec code from your manual? Look it up in coolant specs explained.
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Key takeaways
- RV/plumbing antifreeze is for water systems. Engine coolant is for engines.
- Labels often list "burst protection" temperatures, which differ from the freeze point.
- Bypass the water heater so you don't fill it with antifreeze.
On this page
RV antifreeze vs engine coolant
| RV / plumbing antifreeze | Engine coolant | |
|---|---|---|
| Used in | Fresh water lines, traps, tanks | Engine cooling system |
| Base | Usually PG and/or ethanol | Usually ethylene glycol |
| Engine inhibitors | No | Yes |
| Toxicity | Labelled non-toxic (still don't drink it) | Toxic (EG) |
| Color | Often pink | Various |
Burst vs freeze protection
RV antifreeze labels often show a "burst protection" temperature, the point at which pipes are protected from bursting, even though the fluid may turn slushy at a warmer temperature. Use a product rated for your coldest expected temperature, and don't dilute it unless the label allows. The figures are on the label.
How to winterize an RV step by step
- Drain the fresh water tank, water heater and low-point drains.
- Bypass the water heater (bypass valves or kit).
- Connect the pump-converter or tank to the RV antifreeze jug.
- Run the pump and open each faucet (hot and cold) until pink fluid flows, then close it.
- Flush the toilet until pink appears.
- Pour some into each drain trap.
- Follow your RV manual for ice makers, washers and outside showers.
Common mistakes
Common mistakes
- Filling the water heater with antifreeze. Bypass it.
- Using automotive coolant in water lines. It's toxic.
- Putting RV antifreeze in the engine. No engine protection.
Engine coolant for the RV's engine
The RV's own engine or generator needs engine coolant to its spec. See what coolant does my vehicle need? and heavy-duty coolant.
How much RV antifreeze does winterizing take?
The amount depends on the size of your RV's plumbing and whether you use a water heater bypass. Bypassing the water heater saves a large volume, because otherwise you'd need to fill the whole tank. Your RV's manual often states an estimate. If not, have extra on hand and stop once every faucet, the toilet and every drain trap shows pink fluid.
Blowing out lines with compressed air
An alternative or addition to antifreeze is blowing water out of the lines with low-pressure compressed air through a blowout plug. It reduces how much antifreeze is needed, but traps and some fixtures still hold water, so many owners still add antifreeze to traps and drains. Use low pressure as recommended by your RV maker to avoid damaging the plumbing.
De-winterizing in spring
- Remove the water heater bypass (return the valves to normal).
- Connect to fresh water and run every faucet until the water is clear and free of antifreeze taste.
- Flush the toilet several times.
- Sanitize the fresh water system if your manual recommends it.
- Check for leaks at fittings and the water pump.
Choosing an RV antifreeze
- Burst protection rating suits your climate.
- Labelled for potable water systems.
- PG-based vs ethanol-based: check the label and your RV maker's preference.
- Ready to use (most are), so don't dilute it unless the label allows.
Understanding "burst" ratings on the label
RV and marine antifreeze products are commonly sold with burst-protection ratings such as −50 °F or −100 °F (for example, Star brite markets a "Winter Safe −100°F" product). The figure is the temperature down to which the product is claimed to protect pipes from bursting. The fluid may become slushy at a warmer temperature. Product makers generally say not to dilute these products, because dilution reduces protection. Choose a rating suited to your climate and follow the label.
Related tool
Not sure which coolant your car takes?
Find your coolant →Faucets and fixtures
Faucet makers publish their own winterization steps. Lippert's RV faucet winterization sheet is one example. Some faucets and fixtures hold water in cartridges or low points, and the procedure may include opening both hot and cold sides and leaving handles in a specific position. Check the documentation for your fixtures, the water pump and any ice maker or washer.
Antifreeze or air blowout?
| Method | Pros | Cons |
|---|---|---|
| Antifreeze only | Simple; protects traps and fixtures | Uses more fluid; flush in spring |
| Air blowout only | Less fluid, easier spring start | Traps still hold water; risk if lines aren't fully cleared |
| Both | Belt and braces | More time |
Don't confuse it with engine coolant
RV antifreeze (usually pink, PG or ethanol based) has no engine-cooling inhibitors and must not go in the engine or generator. Engine coolant (often ethylene glycol) must never go in fresh-water plumbing. Keep the two in clearly labelled containers. Prestone, for example, publishes separate guidance for winterizing systems.
Spring checklist
- Reconnect or reset the water heater bypass
- Flush every faucet until the water runs clear and tastes clean
- Sanitize the fresh water system if the RV maker recommends it
- Check for leaks at the pump, fittings and fixtures
- Dispose of collected antifreeze per local rules
Common mistakes
Common mistakes
- Diluting RV antifreeze. It reduces protection.
- Forgetting the outside shower or ice maker.
- Leaving the water heater in-line. It wastes fluid.
Bottom line
Use undiluted, potable-rated RV antifreeze with a suitable burst rating, bypass the water heater, and flush thoroughly in spring.
Real-world scenarios
| Scenario | What it likely means | What to do |
|---|---|---|
| First winter with a new RV | Unknown plumbing | Follow the RV maker's procedure |
| Pink water from a faucet in spring | Antifreeze remaining | Keep flushing |
Estimating how much to buy
Count the fixtures that need protection (faucets, shower, toilet, outdoor shower, ice maker, washer) and the drain traps. Bypassing the water heater saves the most fluid. Buy a little extra, since unopened jugs keep for the next season.
Short checklist
- Bypass set
- Every faucet pink
- Traps filled
Repair manuals & accessories
Tools for this job
4-in-1 antifreeze refractometer (EG and PG scales, ATC)
Reads freeze protection from one drop, on separate ethylene and propylene glycol scales.
Examples of the tool type, not a test or ranking by us. Check fit and instructions before you buy. See the full cooling system tools guide.
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Next step
Not sure which coolant to buy? Match the spec code in your owner's manual, then buy the coolant that lists it.
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