RMI-25 Cooling System Treatment
From $35.00 incl. GST
RMI-25 is a powerful coolant additive designed to improve the performance of your entire cooling system. It delivers superior cooling compared to glycol-based and waterless coolant options — and at a much lower cost. If you don’t need antifreeze, you don’t need glycol.
- Engines run cooler, even under load
- Outstanding cleaning ability across the entire system
- Lubricates water pump seals, heater valves and moving components
- Guards against corrosion, electrolysis and rust build-up; doubles hose life and protects seals
- Can be used with straight water, distilled water, or conventional coolant
- Non-toxic, biodegradable, low-cost concentrate with proven results
- Description
- Reviews (60)
- Instructions
- Video
- ASTM Testing
- SDS
Description
RMI-25 is a cooling system treatment that makes engines run cooler and protects the whole system. It lowers coolant temperature by 7°C or more, cleans scale and rust, and guards against corrosion, electrolysis and cavitation. It lubricates water-pump seals and doubles hose life. You can run it with straight water, distilled water or conventional coolant. It is non-toxic and biodegradable.
The RMI-25 cooling system treatment helps your engine run cooler and stay clean. Water cools better than glycol coolant in typical Australian conditions. Because even thin scale blocks heat transfer, engines overheat over time. RMI-25 removes that scale and lowers coolant temperature by 7°C or more.
It does more than cool. It cleans scale, rust and sludge from the radiator, block and heater core. In addition, it lubricates water-pump seals and valves. As a result, hoses and seals last longer and pumps fail less often.
The RMI-25 cooling system treatment also protects the metal in your system. It guards cast iron, aluminium and copper against corrosion and electrolysis. It also prevents cavitation pitting in pumps and liners.
- Runs engines cooler, even under load
- Cleans scale, rust and sludge
- Stops corrosion, electrolysis and cavitation
- Lubricates seals and doubles hose life
- Non-toxic, biodegradable and low cost
You can use it with straight water or with conventional coolant. Choose the RMI-25 cooling system treatment to cool and protect your engine.
Engine overheating?
Overheating happens when your radiator, block or cylinder heads can’t shed heat properly — often from scale, rust or poor heat transfer.
RMI-25 will cool it by 7°C — or more
Water cools more efficiently than glycol coolants, which aren’t necessary in typical Australian conditions. (Waterless coolants are essentially pure glycol, and your engine runs hotter.)
Even a thin layer of mineral scale in the radiator and water jackets reduces heat transfer and raises temperature. That causes hot spots, inefficient cooling and, in severe cases, engine failure.
RMI-25 lowers water’s surface tension for better heat dissipation and thermal conductivity. The result is noticeably cooler coolant temperatures, especially on hot days, when towing, or under heavy load.
Proven results in harsh conditions
Toyota Landcruiser fleet: Over 100 vehicles in harsh, hard-water conditions suffered about 25 water-pump failures a year from worn seals and cavitation. After switching to RMI-25: Year 1, only 1 failure; Year 2, zero. It protects against cavitation erosion and extends water-pump seal life, cutting costly downtime.
RMI-25 cleans, lubricates and protects the whole cooling system. Instead of replacing expensive coolant, add it to your system and let it work as you drive. It improves cooling efficiency, reduces overheating and extends engine life.
Simple to use
One easy application — pour the required amount into your radiator, top up if needed, and drive.
- Non-toxic system cleaner
- Corrosion protection for all metals
- Inhibits electrolysis and rust
- Prevents water-pump failures
- Doubles hose and seal life
- Protects against cylinder pitting and cavitation
- Fluorescent leak detection for easy testing
- Cost-effective alternative to glycol coolant
If antifreeze isn’t required, run straight water with RMI-25. For best results use distilled water to minimise scale. For remote travel, the cooling system can even serve as an emergency water source (only once all glycol is fully flushed).
Savings history
- Water-pump failures costing $300–$4,000
- Major engine damage and rebuilds from $4,000 to over $200,000
RMI-25 coolant additive
Many cooling-system products fail to stop scale, corrosion or sludge. RMI-25 works differently: it breaks scale, rust and solids into microscopic particles and keeps them suspended, which may temporarily discolour the fluid.
Within 6–10 hours you may notice a colour change. When you do: drain, flush, refill and re-dose. Repeat until the fluid stays clean — that shows the system is restored.
RMI-25 works with conventional coolant and antifreeze, glycol-based systems, or straight/distilled water. It cleans the whole system, including the heater core, radiator, hoses and internal passages.
Complete system protection
- Prevents corrosion, rust and scale
- Stops cavitation erosion in pumps and liners
- Protects against cylinder pitting
- Lubricates seals, valves and fittings
- Extends hose, seal and component life
RMI-25 is non-toxic, biodegradable and safe for use in environmentally sensitive areas. Unlike products that mask problems, it actively cleans, protects and improves cooling across the whole system — from everyday cars to heavy-duty machinery.
60 reviews for RMI-25 Cooling System Treatment
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Directions for use
Add RMI-25 directly into the radiator.
- 250mL treats 20L
- 1L treats 80L
Blocked or corroded systems will be cleaned within 15 hours of regular driving. Excessive corrosion or blockages will float to the surface and can be removed or flushed from the overflow tank.
RMI-25 replaces the need for regular coolants.
Summary – Independent Testing & Real-World Results
RMI-25 has undergone independent laboratory analysis using recognised ASTM methods, confirming acceptable wear metals, stable chemistry, and system cleanliness under operating conditions.
RMI-25 – Independent Laboratory Testing Results
RMI-25 added to glycol has been independently analysed using recognised ASTM test methods covering wear metals, contaminants, chemistry, and electrical characteristics. Results indicate stable system condition with key parameters within acceptable guidelines.
Complete ASTM test results (independent laboratory)
| ASTM Method | Test Area | Parameter | Result | Guideline / Expectation | Status |
|---|---|---|---|---|---|
| ASTM D5827 | Wear Metals | Copper (Cu) | 5–6 ppm | Typically ≤5 ppm | PASS / MONITOR |
| ASTM D5827 | Wear Metals | Iron (Fe) | <1 ppm | <5 ppm | PASS |
| ASTM D5827 | Wear Metals | Lead (Pb) | <1 ppm | <2 ppm | PASS |
| ASTM D5828 | Contaminants | Silicon (Si) | 28 ppm | <50 ppm | PASS |
| ASTM D6100 | Additive Elements | Sodium (Na) | 3909 ppm | Coolant dependent | INFO |
| ASTM D6100 | Additive Elements | Potassium (K) | 3568 ppm | Coolant dependent | INFO |
| ASTM D1287 | Chemistry | pH | 7.1 | Acceptable range | PASS |
| ASTM D1125 | Electrical | Conductivity (EC) | 4.71 | Acceptable | PASS |
Frequently Asked Questions
Has RMI-25 been independently tested?
Yes. RMI-25 has been analysed by an independent laboratory using recognised ASTM methods, including wear metals, contaminants, chemistry, and electrical testing.
What do the results mean in practical terms?
The results indicate stable system condition with no abnormal contamination detected. Wear metals are within acceptable ranges, with copper at the upper guideline threshold and recommended for routine monitoring.
Click here to view the RMI-25 Safety Data Sheet
Peter Lane –
Always very informative and looking to the future to keep vehicles running like or close to new
Thomas Beaton –
MN Triton getting hot on hot days.
Used the RMI25 and instantly worked.
Average before use was around the 95 mark and big hills made it jump even higher. after use average is 88-92 so it 100% works will be buying once I need again and their other products too.
Gerard Lowe –
Excellent product
Ryan Gosling –
I’ve always been a bit sceptical of coolant additives but within 1000 k’s of using this product it’s proven itself to be true. descaling all the rubbish that was inside my motor out into the overflow bottle. I’m looking forward to using it not Only just in my four-wheel-drive, but also in my race engines and putting the product to my mates for them to use too.
Chris –
Good product working well
Matt Burton –
Top tier product
Michael Seierup –
Seems to clean system as described
Anne –
Used before good product
eric henry –
Been using it for years
Isaac Murphy –
Haven’t tested it’s cleaning ability but definitely keeps temps down when mixed with demineralised water at the recommended dosage….. should help with coolant temps flogging down the soft sand when the swell is up
Anthony –
Haven’t used this latest delivery yet, but over the years, it has served me well.
Van Huys –
Good product
Darryl Shorten –
I am a return user of this product and use it in my ski boat. Amazing
Matthew –
Easy to use, very effective.
Robert Forrest –
Did the head gasket on my 2011 Ranger and used a well known brand of radiator cleaner before I started. Car is back together and put your RMI-25 in the newly flushed radiator. After 20 minutes of running the water was brown as s… Lots of floaty bits removed. Going to leave it for a few days running around and flush again. Going to use this on it’s own with water in the future. Amazing stuff!
Damien Westall –
10/10 definitely I’ll buy it again
Norman –
Simply the best product of its type in the world, in my opinion, simply nothing like it, quite unique, it simply works,
Brilliant product.
Adrian Grossman –
Has my td42t running at normal operating temp in very hot and humid conditions, especially when working it hard. Does the job and I keep coming back to cost effective maintenance products because they just work.
Brian Bowden –
Easy to add to my cooling system. Too early to confirm improvements. However I am confident it will perform as well as the other products I use from CEM.
Michael Schipp –
So far it has been doing as per video and recommended 👌
Dave Walker –
Awesome so far. Cheaper than coolant so far.
Bob –
Seems to work very well
James Mcdonald –
Great service.Great advice Great value
Wesley Atkinson –
Very good product
Stefanie Hess –
Seems to be doing what was stated on the bottle
brian Cottell –
another top product, performs as stated,have not used glycol based cooling products for years,antifreeze not required in the flinders ranges.
cannot stress how good this rmi-25 is,use in all our cars and utes and older classic cars.
never had any problems with it .
we dont just like it we love it.
Jackson Wise –
Highly recommend
Hughen McConaghy –
Has made a difference. Does what it claims.
Simon –
I am still evaluating this product but have confidence with CEM products.
Mark Hoefler –
Well it’s been great so far ,seen the improvement after our first long drive ,cooler
Sir John kettleson –
Deletes the kettle from the td
Tim Law –
With around 6 hours of driving since I added RMI-25 to the HJ61 Landcruiser with 12HT engine and 7 year old cross flow PWR radiator, I can see a 10°C improvement in cooling in like for like conditions. I have a sensor on the top and bottom tanks and was previously seeing only a 10°C drop across the radiator when towing my van at 100kmh in mid 24°C ambient. Now this difference is 20°C and often more – all before the suggested 10 hours of running and with no flush yet. Looking forward to further testing in warmer ambient conditions.
Frank barone –
Feed back. I did treatment of cooling system rmi-25. On my India 4 wheel drive 2.2tubo diesel tata xenon.
I could not believe now much the temp reduce after run along the free I was surprised. Excellent product.
Richard –
the product works as it says it does am very happy
Kwang Poh –
excellent service from the well-informed support staff.
Nathan Trezise –
What a great product that does as described. i have a 1955 FJ Holden, we all know they used to run warm. so i added a dose of RMI 25 to the coolant that was in it and ran it around until it discoloured as described. a drain and a back flush and refill of water and only RMI25 an the ole chap now runs the coolest it ever has. 35 degree day, arh no worries, the old grey engine still keeps it cool. I no longer have to keep an eye on the temperature. its been months now and has barely discoloured since not bad for a cast engine. Super wrapped.
Highly recommended even in the old classics.
Anthony Lorimer –
great product and does exactly what it states
Jamies –
Good gear
Mike Garner –
Quick and effective
Thomas Slemenda –
So far so good. Just put it in so I’ll find out in a couple of weeks. But sounds like a good product.
David Wall –
Used this in 2005 TD42TI Gu Patrol.
The factory temp gauge would sit in the upper end of the range when driving at 110kph for long periods.
For reference i live in the NT.
I drained the cooling system and used RMI 25 with distilled water to fill it up.
I drove 650kms from Katherine to Boroloola today(05/12/2023) with outside temps pushing 40 odd degrees.
Coupled with the RMI 25 and the new larger intercooler scoop, i was able to maintain 115-120kph the whole way.
No longer having to drive to the temp gauge. The temp did creep up on a couple of hills when the cruise control was set to 120, however the needle only went up about one needles width, nothing like before where i would be required to back off.
Great product.
Highly recommend
Edward Cook –
Haven Cook – August 15 2023
Had a Hino P10 come in with oil coming out of the cooling system. Checked engine and decided it was the engine oil heat exchanger in the side of the engine. We couldn’t get a replacement oil heat exchanger so we dosed the cooling system with the recommended dosage of RMI-25 and took it for a 20 minute drive. Drained the cooling system. Then dosed the cooling system again and sent the truck back to the customer. We got the new heat exchanger in 2 weeks later, but the customer couldn’t get the truck back for 4 weeks. We checked the overflow bottle and it was almost full of oil. When we removed the radiator cap there was no oil on top of the coolant. We drained the coolant and removed the heat exchanger and found no traces of oil in the water gallery and also no rust deposits. I couldn’t believe it. Good stuff.
John –
Great stuff.
Have been using it in all my vehicles for many years.
So easy to use.
Tyron Nagy –
Liquid gold
Cade Aitken –
Great product
Bob Corbett –
I had it in my PX Ranger now for approximately
120,000 tans the cooling system is performing as it should
BEVAN MAUGER –
Does as it says hoping to extend the life of water pump seal so I have no side of the road repairs whilst travelling
customer –
noticed the difference straight away
Dominic Pepe –
First time using. So far so good.
Terry Cogzell –
Done a great job of cleaning rust stain from my 2002 hilux cooling system after a week or two.
Jack –
Bought some for my td42 nissan patrol mainly to clean the system but the added cooling benefits are great.
Jack –
Bought some for my td42 nissan patrol mainly to clean the system but the added cooling benefits are great.
Matthew Ellis –
I have seen no effect after adding this product, but that maybe because it takes a while to circulate through the cooling system. Modern cars don’t have a radiator cap to make adding easy, so have to add it to the header bottle!
John Athanasiadis –
Had already reverse flushed the block, radiator and heater core with tap water using an adaptor. Put in the RMI-25 in the header tank and finished topping up then bled the air out. At this stage (2 weeks) I have not seen any ‘floaties’ in the header tank (yay) but I had previously been flushing every 3 – 6 months to unblock the heater core. It will be very telling if the heater core stays unblocked with the RMI-25 now in service, and I believe it will.
I also have deliberately only used tap water to really put the additive to the test. Other long term users have done the same (using tap water) with no ill effects and one person informed me that it has been in a cooling system for 5 years with tap water and all is peachey so far. So I will find out myself too I guess after some years!
Didn’t do enough testing before using it but I believe it was running at around 85 celsius previously and now it is 80 -81 (with 82 celsius thermostat) and on a recent foot down uphill push it got to all of 83.
So far I have spent the same as I normally would on normal green concentrate but I believe with better results.
Aaron Taplin –
Works amazingly well – successfully cleans out neglected cooling systems with immediate results shown on the temp gauge. Also works well in our supercharged race car – keeping both engine & charge cooler temps significantly lower than before.
arien scholten –
Used this product for years.
AJ Campers Pantry –
Our 30 year old 80 series Landcruiser like a lot of old diesels had some issues with the heat. We had a Redarc gauge installed to monitor these coolant ups and downs. As soon as we switched to the RMI-25 product we had a drop by 10ºC in engine temperature. Thats a massive decrease and peace of mind when remote touring in the hot Aussie outback.
Wayne Mackenzie –
I just completed a 3000klm trip to Longreach and the radiator ran a lot cooler with the RMI-25 – normally it sits halfway (9 o’clock) but after adding this it ran at 8:30 – a noticeable difference.
AS –
My temperature gauge is definitely not as high as it was since I added this product to my radiator.
John Gilroy –
Great product. I flushed the radiator and engine with it, and then added it to the water as this can be used in lieu of glycol/coolant.