Hope this question isn't redundant. I did try to use the search box, but all terms I tried returned 0 results.

Has anyone here tried Zerex G48 in their coolant system? It's HOAT, low-silicate, phosphate free, and blue like Volvo type-C. Also the back label says it's Volvo approved. The reason I'm curious is that I found no reference to G48 on the Volvo forums I searched, and that seems odd since this coolant seems like a perfect fit.

Maybe I'm missing something?

Any experiences and opinions appreciated.


I drive a 1991 245 automatic with 245K+

g05 and g48 are very similar. it's mostly just color. g05 was the spec for volvo starting in 1980 because of the diesel engine. up until 3-4 years ago, g05 was also the spec for mercedes. they then changed to g48. i did not know the official volvo spec changed to g48, but i would not hesitate to use either. fyi, g48 has been the spec for bmw forever. good luck, chuck.

Not entirely sure, but despite it's fancy name and conspicuous "approved" print, it's just standard coolant, to be replaced every 2 or 3 years.

Hilariously it says "Compatible with glycol coolant." It's good to know that all coolants are glycol based, even the G12 type (VW/Audi) that supposedly lasts the life of the car.

The differences are in the additives, so stick to one brand/type and don't mix in other stuff. Important: stick to Volvo recommended change interval. For these old engines, that's going to be two years. So, the cheapest coolant should suffice.
No point in using stuff that would last 5 years, that's for engines that the manufacturer also recommends a 5 year change interval for.

I've used the cheapest generic blue stuff I can find for the past ten years, and it's just fine. I always flush the system with tap water and always find that a little bit of silt comes out. Extending the interval too long could cause this silt to build up and block things.

Oh yeah... many manufacturers specify a proprietary coolant, but let's face it, that's just to make some extra money.

hi polar- this is always an interesting question. when i bought my 92 245 in 11 it had clean green coolant in it and a rebuilt cylinder head. just before i bought it the head gasket had blown to hell and the head surface was deteriorated. coolant is still green and clean and 5 balls are still floating in that little tester (almost 30k miles). many have told me green gunks up the system with thick white silicate and phosphate swill. have seen no evidence of this. fla gets hot as holy hell in the summer and have noticed no overheating. green a freeze is permissable in 240s according to prestone and zerex. have a gallon of G 05 zerex antifreeze on the shelf and it is listed as ok for volvos. in the next year i will flush the system and may replace with the G-05. a few have told me G-05 may cause leaks in the old 240. not sure what to think. what think you? thanks tons oldduke

Colourant is just another ingredient in coolant. It may be used by manufacturers to make it easy to distinguish between different types, but it tells you exactly nothing about the composition. If for some reason in the past it had been decreed that all coolant be blue, then all the different formulas would now simply be blue.

Clean looking coolant only means that solids have been deposited, it may not mean that there aren't any. I make it a point to flush the system with running tap water before I put in new coolant. The radiator I take out and flush upside down, that helps dislodge deposits. The first flush water coming out is always a little cloudy, even after just 2 years.

The tester tells you only about frost protection, it doesn't say anything about the other ingredients like the important corrosion inhibitors. These have a limited lifespan and get less effective faster than the coolant will loose its frost protection. I don't even have a tester.

Renewing the coolant at the recommended interval is especially important on engines that combine an iron block with an alloy head (like our red blocks). Where different metals meet, electrolytic corrosion is always possible (as Land Rover Defender owners will tell you). I will not risk that for the relatively little effort and cost a coolant change entails.

One may argue that the car manufacturers recommendations were based on what was available at the time. If in the 1980s the best coolant had an expected lifespan of 2-3 years, you obviously won't find any recommendations exceeding that.
Does that make it right that you now use Zerex G-05 and make it last five years?
I don't know, but I do know that modern formulations may use ingredients that might not be very compatible with some materials used in the past. Or have more detergents that wash away deposits that were actually plugging (small) leaks...

Coolant is hardly "rocket science" so manufacturers like Valvoline come up with attention attracting packages and marketing and shout about special features and long life and so on. But look around on their websites and what do you see... texts like this:
Replace your antifreeze when recommended by your vehicle’s manufacturer to help minimize your risk of radiator failure and expensive repairs.
And to me, that's the one bit of advice definitely worth taking.

Long story short: drain the cooling system, flush, drain and fill with one specific brand and type of coolant. Repeat when Volvo recommends.
Since these old enigines have such a short (2 years) interval, I use the cheapest stuff I can find (€ 1,50/litre) and it has worked out fine for me for the past 11 years and 100,000 km.

hi polar and jw- have you heard anything about the highly recommended zerex G05 promoting leaks in the 240 red block cooling system. on the fence about staying with green prestone or zerex or going to the G05. suspect advertising info is propaganda ,puffery and poppycock. soon going to flush my green coolant; been in there 5 years. thanks tons oldduke

Strolling around the internet, I mostly found opinions of different coolants, but not many facts.

Fact: Volvo specified "Volvo coolant type C" in a 50/50 mix. This is supposed to be blueish green.
I don't use it.

I have not found any comments on Zerex G-05 promoting leaks.
Fact: the datasheet says: "Effect on nonmetals: No adverse effect". If any leaks are going to occur, they would most likely start on the nonmental parts like hoses and seals.

The one thing most often agreed upon is not to mix different types. So if you're switching to the G-05, make sure that all old coolant has been drained and the system has been flushed. You may want to make sure that the heater matrix is not retaining any old coolant.

G-05 is approved for use in all Volvos. You should be fine.

Added bonus is flushing will also clean your radiator, heater core, water pump and possibly extend their life. Check your hoses condition and replace questionable hoses before doing this. Hoses deteriorate on the inside too so flushing won't help bad hoses or your cooling system for long...