Coolants, fuels, lubricants- everything is a sensitive issue for your car, especially the coolant. Zerex G40 and G12 are the two most common coolants people use.
G40 works better in higher temperatures, has better protective properties, and is pricier. G12 works better in a lower temperature, has good protective properties, and is more affordable.
Picking the right coolant for your car can be hard especially if you have older models. And putting the wrong one in does more harm than good.
So which coolant is for your car? Here’s a detailed breakdown to help you out.
A Quick Summary Of The Comparison
| Feature | Zerex G40 Coolant | G12 Coolant |
| Specs and model range | Good temperature range supports more engine models | Better temperature range supports fewer models |
| Protective properties and lasting time | Better, doesn’t wear off quickly | Good, wears off quicker |
| Price and availability | Pricier but easily available | Affordable, harder to find |
Key Differences Between Zerex G40 And G12 Coolant
Both coolants are amazing but in a different senses. Specs and model range, protective properties and lasting time, price, and availability- these are the major differences between G40 and G12.
- Specs and Model Range
Both have pretty solid specs (which is why they’re so popular) but there are definitely some big differences.
G40 is better for a warmer temperature range and is compatible with almost all new models.
G12 can do better in a broader temperature range but is compatible with fewer models.
Zerex G40 is good for warmer climates.
It will protect your engine from winter freezing up to -34F and prevent summer heat issues till 265F.
Zerex G40 is compatible with pretty much all new models but that’s not all. This coolant is also backward compatible meaning it also works for older models.
Even though the range of older car models is pretty small, the overall model range is pretty good for G40.
G12 on the other hand is better for more chilly climates. It can protect your engine from winter freezing even at -58F. As for summer, it will protect your engine up to 245F.
The upper-temperature limit might be a little lower compared to G40 but the overall range is pretty impressive.
G12 is mostly compatible with older car models, it doesn’t go with the newer ones. So the list of compatible models is pretty short for G12 coolant.
- Protective Properties and Lasting Time
Protective properties are more of an added benefit when it comes to car coolants, but it is impressive. Zerex G40 gives better rust protection for your car, and it doesn’t need changing much.
G12 is pretty far behind in protection properties and needs to be changed more.
G40 is a Si-OAT coolant. They’re made to give you the best of both worlds- better protection against rust and corrosion and a long-lasting service time.
And it does both of these pretty well. G40 doesn’t wear off too fast and the buildup is very slow. So you won’t have to replace it too frequently.
G12 on the other hand isn’t the best when it comes to protecting the system. The protection properties only activate when it comes in contact with rust.
Meaning it will either be already late, or there has to be pre-existing rust for it to work. It also has a faster buildup rate, so you’ll have to change it more frequently.
- Price And Availability
This is the biggest difference between these coolants. Zerex G40 retails for around $17.99 at Walmart.
G12 goes retails for $7.94-$20.99 depending on the brand. The only problem is, the original G12 has been discontinued. So you’ll have to look at alternatives or different brands.
Which Coolant Is Better Fit For Your Car?
That’s an easy question to answer in most cases, but not in this one. While both Zerex G40 and G12 are high-quality products, they aren’t interchangeable.
So it is hard to make a head-to-head comparison and declare an outright better choice.
The answer isn’t hard, but it is complicated for sure.
If you own a newer model and the manual recommends G40 coolant, you can go with Zerex G40.
This coolant is compatible with pretty much all new models and lasts a pretty long time too.
Plus it is backward compatible so you won’t have to worry too much. The best feature of this coolant is its protective properties.
Zerex G40 will give your engine protection against rust and corrosion better than G12. It is a little pricey, but you can find them pretty easily. Even your nearest Walmart might carry this.
If you own an older model and the manual specifies G12, then you’ll have to go with exactly that. G12 is known for its service time (which is pretty long).
You won’t have to change it because it wore off, it will be more because of the buildup.
The problem is, the original G12 is currently discontinued.
So if you still have some left in your system and need a topping off, you’ll have to look for something compatible with it (which is going to be very hard to find) or drain it all and go with a new coolant.
In that case, Zerex G40 would be a good option.
Overall, Zerex G40 is the better fit for your car in terms of versatility. But if your car manual specifies G12 and you can get your hands on it, you should continue using it.
Also Read: Reasons Behind Take 5 Oil Change Is So Expensive.
Frequently Asked Questions (FAQ)
No, they aren’t the same thing or substitute for each other. But G40 has a high chance of being compatible with your G12 model. Zerex also recommends G40 for VW G12++ vehicles.
Zerex G40 is approved by TL 774-G OEM. If your car model is compatible with that, you can use G40 in your VW.
Pentosin SF is a compatible coolant (also the closest substitute) with G12. Other than that, G12 could be mixed with G12++ but the protective properties might decrease.
No, they’re different. But some mechanics suggest G30 as an alternative to G12.
Final Verdict
Choosing the right coolant is a tricky business unless you want your engine to give up early. Zerex G40 and G12 both are good, but they’re also case-specific.
In the Zerex G40 and G12 fiasco, G40 is a better choice because it is more versatile. But if you can find some G12 and your manual specifies it, stick to it.
