Coolant explained

OppolockGrumpy @Oppolock Colliwobble, Gippsland. Vic
edited March 2017 in Articles & Guides
I get a lot of assorted Tech bulletins I have subscribed to over the years because things change often and I like to stay up on whats what.

An interesting article came my way compliments of Europarts and I think its a pretty fair explanation of coolants and the types plus why they are different.

Its basically an Advert for their Genuine Mercedes Benz citric acid flush but with a really good explanation.

On the older red block cars you can be a bit flexible but with the White block cars especially those laden with sensors it pays to stay on top of coolant and check things like the gravity of the mix on a regular basis (Like a Hydrometer for coolant).

its also worth noting that adding coolant to a car that hasn't had it for a while can cause issues as it will soften rubber and gaskets a lot of the time so if you DO want to add Coolant to a Non coolant car start swapping out the hoses and watch the head gasket.

Green, Orange, Yellow, Blue…What color coolant should I buy??
Posted on January 15, 2015 by
What color anti-freeze should I put in my car

Engine coolant, like many other fluids, is not a lifetime thing. It gets old. When it does, the protection decreases exponentially. Interestingly enough, however, the anti-freeze capability of the coolant does not. Coolant is special for two reasons that differentiate it from pure water:

-It contains Anti-Freeze, an alcohol based additive that keeps it from freezing (obviously), usually propylene glycol or ethylene glycol. Commonly mixed 50/50 with distilled water.

-It will also contain a variety of different additives that keep it from eroding, corroding, and leaving crusty deposits in your engine block.

Since engine blocks are nearly always made of iron, running straight water will quickly result in a rusty mess. The expansion tank will go from clean to orange to brown in just a couple of days. To combat this, a few additives are put in. This usually includes silicates and phosphates to protect against scaling and corrosion. When you buy a bottle of concentrated coolant, Most of this is the anti-freeze glycol, while only a very small percentage (in the single digits for most brands) are these additives. Even though they are in very limited doses, these protective additives are what you are paying attention to when you decide what coolant to put in your car, as they affect different cooling system metals differently.
volvo antifreeze

Genuine coolant is always a safe bet, but can be pricey
What color coolant should I put in?

Before doing anything, it’s a good idea to check your owners manual. If it calls out a specific coolant, you already found your answer. As with sparkplugs, coolant is one of those things that are best kept to the manual, so follow it’s words and you should be in great shape. Another quick way, although less reliable, is to see what is currently in the car. I say less reliable because many times previous owners will flush a system with the wrong coolant (usually when changing a cooling system component) and be unaware of their mistake. Some types of coolants aren’t compatible with each other.
Can I mix different colors?

The ultimate answer is no. Mixing different styles of coolant can lead to accelerated degradation of your cooling system and can cause all sorts of problems. To best understand this, it’s a good idea to do a quick explanation of what the different types are. Coolant color is NOT a sure fire way to tell what kind of coolant is in the car, the type of corrosion inhibitors used ARE.

Green and yellow has been around for awhile, and uses the older style inorganic acids for their corrosion inhibitors, including silicates and phosphates. This coolant was designed with older style cooling systems in mind, such as ones that have yellow metals like brass and copper in their systems. Generally, this should be changed every 35k miles or 3 years due to the inhibitors being used up. Once these inhibitors drop out, you will experience buildup in all narrow passageways, specifically radiators and heater cores.

- Contains silicates and usually phosphates

- Also called IAT’s for Inorganic Acid Technology

- Do not mix with Orange/Red/Pink/Blue

These are the other side of the coin. Orange coolant is a modern style of anti-freeze that contains organic acids as their corrosion inhibitors, and usually uses ethylene glycol as it’s main anti-freeze component. Dex-Cool orange coolant is used in many new GM cars (SAAB), and has been adopted by several other manufacturers due to its long life and good protection on aluminum cooling systems, as well as high compatibility internationally. This new type of coolant is meant to be changed at intervals of up to 5 years or 150k miles!

- Contains no silicates or phosphates, instead the corrosion inhibitors consist mostly of this million dollar word: Carboxylate. Carbocylates are organic based compounds that target specific corrosion spots vs coating the entire system with a protective layer, like silicate and phosphate coolant does. This results in a much longer lifespan, as the inhibitors aren’t used up in the coating process.

- Also called OAT for Organic Acid (or additive) Technology

- This style of coolant should not be mixed with Green or Yellow antifreeze.

- Do NOT use an OAT style coolant in older vehicles, especially since it will eat away the yellow metals and solder used in radiators, pumps, and bearings.
What if my coolant is purple, pink, or blue?
blue mercedes coolant

Pentofrost NF is a silicated European formula that contains no phosphates or nitirites. Blue OAT coolant is common in German cars, and is different from the blue coolant used in Asian cars, which is silicate free.

Coolant colors are not a sure bet, as there are different types of coolants that have the same color due to differences in water quality between continents. For example, coolant in Europe doesn’t use phosphates due to high mineral content in the water. Calcium and Magnesium doesn’t play nice with phosphates, and can cause scaling and buildup. Almost all coolant coming in Asian based cooling systems is silicate free to protect seals. In short, European, Japanese, and Korean coolants will be constructed differently even if they are the same color.

If you can’t tell yet, what you need to pay attention to is if the coolant you are adding contains silicates and phosphates. Most new cars use the silicate and phosphate free orange/red but there are still companies that resist the deletion of these inhibitors in their cooling systems. Further mucking up the landscape is the Hybrid Organic Acid Technology (HOAT) coolant like G-05 which is meant to have the highest compatibility between cooling systems. HOAT coolants are usually phosphate free but still contains a low amount of silicates. There are also NOAT (Nitrite Organic Acid Technology), NMOAT (Nitrite Molybdate Organic Acid Technology) and POAT (Poly Organic Acid Technology) styles of coolant, each optimized for different types of applications and better compatibility.
OK that is a lot of science, so what coolant do I need again?

The coolant that came stock in your car. Your owner’s manual will usually say what type it is, or what rating it is. Just keep in mind that you can’t mix the two technologies (IAT and OAT) and your cooling system will stay healthy and productive for the life of the car. carries genuine manufacturer coolant for all of our supported brands. No longer do you have to go to the dealer to get genuine coolant.
I suspect my car has had the wrong coolant, or old coolant in it for a long time
citric acid flush

Citric acid cooling system flush is designed to reverse damage caused by coolant buildup and scaling. carries a Genuine Mercedes Benz citric coolant flush that you mix with distilled water and run for a short period. It removes deposits and buildup in any cooling system, MB or otherwise. When you are done with the flush, simply add in the correct coolant for your car and enjoy a clean system and hot heater core.

Drain your cooling system and re-fill with distilled water. Pour the citric acid flush in and run the car for awhile, long enough for the mixture to spend time in all nooks and crannies. Be sure to turn your heat on so the flush flows through the heater core. Remember, this is not a good idea to do in below freezing temperatures, as the coolant will have no anti-freeze in it.

- See more at: ... 6vOxX.dpuf


  • I know this is an old thread,but a question for me remains.

    Do i use a concentrate of an anti corrosion,or is a pre mix better than a concentrate?

    Any thoughts?
  • Vee_QueVee_Que @Vee_Que South Eastern suburbs Melbourne.
    You can use Either. Pre mix garuntees the qaulity level of the coolant and the water used to be more pure.
  • Lucky I have a DI water unit at work for all my tanks. Easy to just fill a 25lt container and mix from there
  • Hate to revive an old thread.

    What are people using on the post red block cars?

    Just purchased a gallon of the Volvo concentrate at Peter Warren Volvo. Asking price now $88 excluding GST!! This is up from $65 just 2 years ago (or say 22USD). They did offer at the old price after some negotiation.

    I'm feel forced to purchase this for my XC90 and V50 etc because Volvo refuse to advise whether their formula is HOAT or other. Not happy!

    I use HOAT on my earlier white block cars (850, S90 etc), Penrite 7 year green (Genuine G48 BASF product). My gut feeling is that the Penrite 7 year is the same product technology as Volvos (just green), but with Volvo arrogantly refusing to disclose a spec who knows. Longevity is in the interests of the brand so why not help us look after our cars?

    The whole coolant industry has a lot to answer for, each colour should identify a particular technology and then it would be easy.
  • Ive swapped all of mine via water flush to 50/50 green mix and never looked back

  • That's part of my issue..... Colours have become meaningless. Penrite 7 year is HOAT genuine G48, whereas many green coolants are more basic and use different technologies.

    As per Grumpy's article, it's all about coolant technology. I don't see how Volvo can legitimately withhold the specification of the coolant required on each vehicle. Since they say their coolant is appropriate for ALL Volvos I can only deduce it *must* be HOAT. I've asked Volvo Australia and they refuse to advise.

    What they've ended up with is even enthusiasts are using coolant types based on guessing (and worse, non enthusiasts are dumping anything into their systems. I have a C30 with some GOLD / orange stuff in it), or dump $88 plus on Volvos supposedly secret formula. I can't do that on every car.
  • jamesincJames @jamesinc Oz Volvo Ice Fortress
    Most of the green coolants are fine. Go for the darker looking green ones, like Nulon Long Life. I think the shorter-life coolants just have more water in them or something.

    To be honest I'm messing with the car often enough that I've never had to worry about longevity of the coolant.
  • It's not the longevity of the coolant that concerns me, it's protecting my aluminium heads and blocks from corrosion indefinitely that is the goal. It's choosing a coolant with the right technology for the car, and Volvo won't tell us so we are left guessing. In my mind that's a nonsense act on the part of Volvo. What if they refused to tell us oil spec so we had to buy "Volvo" oil at 3 times the going rate. At least with the Trannies they tell us it's JWS3309.

    I used to just put whatever green stuff was on special and spend the $$$ on good motor oil, but now I've developed a fear of using less than best coolant after loosing two cylinder heads. Granted these were likely due lack of maintenance over decades of previous owners.
  • jamesincJames @jamesinc Oz Volvo Ice Fortress
    Longer-lived coolants tend to correlate with better anti-corrosion properties is what I'm saying.
  • Ive swapped all of mine via water flush to 50/50 green mix and never looked back

    so you just flush water from the mains into the coolant system, which flushes out the old mix, then add the new mix after?
    What about the thermostat not opening? How much of the old water/coolant mix is still within the system? Does that make sense? You might flush the radiator and SOME of the old coolant, but how much is still within the head etc. Hope that makes sense.
  • I use the principal that a drain from the radiator only gets half the fluid out.

    Method 1: Draining and refilling with known same type of fluid.

    Just drain what you can and refill with correctly mixed coolant (50/50), usually about half of system capacity.

    Method 2: Changing type altogether or removing unknown coolant type.

    You need a few drain and fills to remove the old stuff (with the heater on and run engine until thermostat opens. I try to only add hot water to a hot engine when flushing).... perhaps the first couple with free/mains water (unless your in an area with high mineral tap water, Adelaide?) and last few drain and fills should be de-mineralised water to minimise contamination. I've found generally using this method the last drain will get about half of the de-mineralised water out (about 4L of an 8 L system) and you can add straight concentrate to end up with 50/50 in your system.
  • Vee_QueVee_Que @Vee_Que South Eastern suburbs Melbourne.
    You can drain the block on most Volvo motors too. Tap on the exhaust side.
  • jamesincJames @jamesinc Oz Volvo Ice Fortress
    Canoe wrote: »
    What about the thermostat not opening?

    Thermostat is right at the top of the system, whether or not it opens, the only coolant it will leave is whatever is in the radiator top hose. You could always just pop the hose off to finish it off.

    If you're concerned about tap water, distilled water is less than $2/L

  • It's not the longevity of the coolant that concerns me, it's protecting my aluminium heads and blocks from corrosion indefinitely that is the goal. It's choosing a coolant with the right technology for the car, and Volvo won't tell us so we are left guessing. In my mind that's a nonsense act on the part of Volvo. What if they refused to tell us oil spec so we had to buy "Volvo" oil at 3 times the going rate. At least with the Trannies they tell us it's JWS3309.

    I used to just put whatever green stuff was on special and spend the $$$ on good motor oil, but now I've developed a fear of using less than best coolant after loosing two cylinder heads. Granted these were likely due lack of maintenance over decades of previous owners.

    I think your overthinking this way to much
    Ive never seen a single volvo whiteblock head or block corrode out or even show signs of corroding... even after extended dirty water opperation
    The heater core or radiator fail long long before the block or head do when using water and will kill off the motors of the idiot owners from the ensuing overheat

    Volvo did not use a cheap and shit alloy like toyoda that corrodes out a week after you spit on it

    If you really want to protect it futher over using any 50/50 mix then you should fit an annode into the block or head somewhere

    Where i have seen hg fail have been because it was done previously after an overheat and the previous person just did it wrong

    Failing hoses and failing coolant resovoir tanks are the number one killer of p80s at this point
  • edited October 2017
    I think my point was mostly missed. Now Volvo has made matters worse with yet another colour. My point was as per the first post by Grumpy there are different coolant technologies and colour is NOT an indicator of coolant technology.

    True we can mostly get away with *any* coolant with good results, but that's not the point. There is a correct coolant technology for our cars and Volvo REFUSES to tell us what it is.

    To make matters worse Volvo changed from Green to Blue. Most recently it's changed again!

    Below pic is *NEWEST* genuine fluid mixed in Penrite water

    My genuine coolant put into my XC90 3 years ago was Blue, now the genuine coolant (made in Germany) mixed with de-mineralised water is as pictured. That's definitely green!!! WTF VOLVO!!!! Just tell us if it's HOAT, OAT or IAT!!!

    To confuse me even more I've looked at 3 volvo C30'S and including my own (which is getting this fluid) and all had an identical Amber coloured coolant - surely 3 separate C30's wouldn't have an aftermarket fluid which appears identical but different than what I've seen in my other Volvos. My same year (07) V50 has blue, and I am almost certain all these cars the fluid is factory.


    I am surprised nobody else is ticked off that Volvo is insisting we are not entitled to know the spec technology of the fluid. It does matter and they are different, and this rediculous swapping of meaningless colours by Volvo is just making matters worse.

  • Vee_QueVee_Que @Vee_Que South Eastern suburbs Melbourne.
    Penrite etc get the recommendations from the manufacturers and that's what the codes are, they are alloy motors so will still be glycol based, the colour is a non issue Imo.
  • Penrite confirm they have no "recommendation" for the more modern whiteblocks, Volvo refuse to advise the spec.... Even though it is almost certain it is HOAT which means Penrite 7 year and ZEREX G-05 complies (and no doubt many others).

    Volvo changing colours has just compounded the uncertainty created by refusing to give owners the fluid specifications. This is bad all round and I don't know how they can legally or morally deprive owners this information. Even if we are all willing to pay 90 AUD for 4 litres of the special fluid it's not readily available in many circumstances (location, top ups etc).

    At risk of becoming known as the crazy coolant guy, I just hope Volvo read this thread and offer us some enlightenment.
  • OppolockGrumpy @Oppolock Colliwobble, Gippsland. Vic
    I use this now, Red block/White block it doesnt matter.
    But you MUST flush and flush well before you change over or you contaminate the new coolant.
    740/S90/V40t/850 all good BUT flush with the appropriate flushing agent first.
  • Thanks Grumpy :)
  • edited May 2018
    That stuff is a "Universal" product, fine but unjustifiably expensive for no gain in our cars. Had a chat with the Nulon tech guy when it was released and asked him (or non gender person): "couple of my cars I want to last indefinitely (like as long as the pyramids), is this product superior?" He advised it was no superior to any particular formula, but rather formulated for wide compatibility and insisted just using the correct spec for your particular vehicle was the best (I.e. HOAT, OAT etc etc). All in all it is much much $$$ for a product that is not superior to just using the correct SPEC for you vehicle, which as per my earlier rant Volvo doesn't want us to know.

    Personally I've not researched the Nulon varieties much beyond the above (Penrite stickers look better). I have asked quite a few questions from the Penrite tech guy and he confirms the 7 year Penrite (green) is HOAT formulated from a genuine BASF base product. Since the best I can find on the Volvo coolant is that it's HOAT, I'm happy with Penrite 7 year.

    Even Penrite cannot give a coolant recommendation for our modern Volvo's because Volvo refuse to confirm the spec is HOAT. I gather they have recommendations on older Volvo's because they are Waaaay out of warranty.
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