Rotax 912 coolant. What am I looking for?

[danny_galaga]

Engine is 912 uls. I think 2017.

[rgmwa]

Rotax manual has recommended coolants. I use 50/50 Castrol Radicool as recommended previously. That has since been changed to Radicool’s replacement, which I don’t have details of at the moment but it’s in Rotax’s current recommended fluids list.

[danny_galaga]

Cool. So just this stuff

 

https://www.repco.com.au/oils-fluids/engine-oils-fluids/coolant/castrol-radicool-coolant-concentrate-1l-3424673/p/A9458861?rgfeed=true&cid=google-shopping&utm_source=google&utm_medium=cpc&region_id=100352&gclid=Cj0KCQjw0bunBhD9ARIsAAZl0E2rb3iqhcG67iPznsxs4IP52dclHIZeSPIwGuGa4TuL_9suGD7CGAwaAu1oEALw_wcB

 

[facthunter]

There's no magnesium in the system so there's no need  for anything special. It's only cooling the heads. Mix to and maintain the recommended ratio and only mix with pure water if you use concentrate.  Nev

[rgmwa]

1 hour ago, danny_galaga said:

Cool. So just this stuff

 

Has to be 50:50. Those pre-mixed ones may only be 30% coolant.

Here's the list:

https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-016-r12.pdf

[Marty_d]

I notice when you click on that link that Repco also sell "Demineralised" water.  Is it necessary to use that as a mixer or is normal filtered water usable?

 

[rgmwa]

I only use demineralised water to mix coolant. I don't think filtered tap water is acceptable, although others may have a different view.

[facthunter]

Pureau is what  I have used for years. A lot of glycol is not necessary if you are not exposed to extremes of temperature.   Water is a better remover of heat than glycol. The anti corrosion aspect is important, but that motor is less critical than most cars.  It's the corrosion function the relates to the ratio.. Below the minimum specified is not recommended, as it will not give the required protection. Glycol also leaks easily. It will seep out of many places.  Don't risk mixing different types. drain, flush and change if in doubt.  Nev

[skippydiesel]

For many years Rotax have recommended collants which were/are designed for European cars, with multiple differing metals in contact with the coolant (mainly low phosphate spec).

 

Rotax cooling systems have several differing metals in contact with the coolant.

 

Aside from increasing boiling point ("antiboil") and lowering freezing point ("antifreeze") other important functions are;

• the suppression of electrolysis (corrosion) caused an electrolyte (water + salts) and in contact with dissimilar metals (electrode). This can be seen as "pitting" of the coolant galleries (inside cooling system) which can lead to irreparable damage (leaking. etc)
• anti deposit - older coolant would sometimes build up a layer on the wall of the cooling system which could inhibit cooling efficiency
• lubrication of "rubber" seals

 

Up until about 4 years ago, these coolants were not readily available in Australia - they are now. The allowable alternative was "Castrol Radicool" (green in colour) it has done a great job and is still a satisfactory alternative to the newer offerings.

 

Most of the main lubricant/coolant suppliers, on the Australian market, will make a suitable coolant designed for late model European vehicles (& Rotax). . Most  will be RED coolants  Note: The colour of the coolant is no guarantee of compatibility - check the specifications for compatibility.

 

I now use Castrol Radicool SF-O (red) because it is compatible with my various cars & my Rotax - purchased 20L when it was still relativly uncommon.

 

Personally I don't like pre mix coolant - what guarantee do you have of correct 50:50 mixing ratio?

 

I always use "pure water" eg demineralised, RO, distilled and replace at 2 year intervals or according to Rotax recommendation (whichever comes sooner).

[danny_galaga]

2 hours ago, rgmwa said:

Has to be 50:50. Those pre-mixed ones may only be 30% coolant.

Here's the list:

https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-016-r12.pdf

Yes, my link is for concentrate. Demineralised water is cheap enough too

[Blueadventures]

Get Castrol Radicool premixed and get a price from Maxiparts as will be cheapest I reckon. You need about 2.5 litres and premix will be a 5 litre pack.

[onetrack]

Filtered water can still contain a lot of dissolved minerals and compounds that don't filter out - but they will react with metals in engines cooling systems, and assist in electrolysis - so much better to use demineralised water.

[rgmwa]

7 minutes ago, Blueadventures said:

Get Castrol Radicool premixed and get a price from Maxiparts as will be cheapest I reckon. You need about 2.5 litres and premix will be a 5 litre pack.

When I checked Radicool Premix it was only about 30% strength not 50% so check before buying.

[Blueadventures]

24 minutes ago, rgmwa said:

When I checked Radicool Premix it was only about 30% strength not 50% so check before buying.

Not sure; the data sheet for Radicool premix I read was water percentage at 40 to 50% and sg 1.07.  And freezing at the 50% is listed; therefore assume close to 50:50 mix.

[rgmwa]

Maybe, but the one I looked at was a lot weaker than that. I got the concentrate and mixed my own. It’s cheap enough that saving a few dollars is hardly worthwhile. 

[Blueadventures]

2 minutes ago, rgmwa said:

Maybe, but the one I looked at was a lot weaker than that. I got the concentrate and mixed my own. It’s cheap enough that saving a few dollars is hardly worthwhile. 

Same here, glad it's good for 4 years as getting harder to obtain the concentrate.

[danny_galaga]

Repco are showing the concentrate. Forgot to pop in today but will tomorrow 

[skippydiesel]

If you are having problems finding Castrol SF concentrate, check out some of the other brands eg Nulon, Valvoline, Shell, Penrite.

 

NOTE: Coolant used should be a low silicate & nitrite free formula

 

Most coolants specified for modern European sourced engines, will meet the Rotax standards but be sure to check.

 

 

[Carbon Canary]

18 minutes ago, skippydiesel said:

If you are having problems finding Castrol SF concentrate, check out some of the other brands eg Nulon, Valvoline, Shell, Penrite.

 

NOTE: Coolant used should be a low silicate & nitrite free formula

 

Most coolants specified for modern European sourced engines, will meet the Rotax standards but be sure to check.

 

 

Sodium nitrite is one of the most commonly used ingredients for closed cooling system anodic corrosion protection, particularly when there is a significant concentration of chlorides in the cooling water.

 

Why the need for a nitrite free formula ?

[danny_galaga]

Seems to me if I just go with the Castrol gear previously mentioned, which available from Repco I should be golden. It also means if I'm travelling and find i need more I can get it from many car parts stores.

 

Heh. If my plane ever gets to the point I can fly it anywhere...

[skippydiesel]

50 minutes ago, Carbon Canary said:

Sodium nitrite is one of the most commonly used ingredients for closed cooling system anodic corrosion protection, particularly when there is a significant concentration of chlorides in the cooling water.

 

Why the need for a nitrite free formula ?

That's what the latest Euro standards are and what Rotax (a Euro manufacture) have based their recommendations on.

 

You should not be using water with any impurities.

[onetrack]

Brazed aluminium radiators are the reason why you require nitrite-free coolant in todays world ......

 

https://www.chevronlubricants.com/en_us/home/learning/from-chevron/industrial-machinery/nitrited-or-nitrite-free-coolants.html

 

One of the things I've found after long experience and many tears, is that using the coolant either manufactured by the engine manufacturer, or the brand recommended by them is vital - as only the engine manufacturer knows the entire list of metals, alloys, potential corrosion sources, and origins of potential electrolysis in their engines - whereas independent coolant manufacturers may not have this sum knowledge.

 

Another thing to ensure is that there's no stray voltage that can utilise engines or radiators as a path to ground. Even tiny amounts of stray voltage running through your engine or radiator can create electrolysis.

 

Thus, ensure that all necessary earth straps are fitted, and that the earth strap connection points are clean and bright.

[facthunter]

It shouldn't be difficult to isolate the radiator entirely as it's rubber mounted.. . Go air cooled and have less trouble. .  Nev

[facthunter]

The only thing liquid cooled on these 9xx motors is the heads. All that effort for just that. Nev

[skippydiesel]

27 minutes ago, onetrack said:

Brazed aluminium radiators are the reason why you require nitrite-free coolant in todays world ......

 

https://www.chevronlubricants.com/en_us/home/learning/from-chevron/industrial-machinery/nitrited-or-nitrite-free-coolants.html

 

One of the things I've found after long experience and many tears, is that using the coolant either manufactured by the engine manufacturer, or the brand recommended by them is vital - as only the engine manufacturer knows the entire list of metals, alloys, potential corrosion sources, and origins of potential electrolysis in their engines - whereas independent coolant manufacturers may not have this sum knowledge.

 

Another thing to ensure is that there's no stray voltage that can utilise engines or radiators as a path to ground. Even tiny amounts of stray voltage running through your engine or radiator can create electrolysis.

 

Thus, ensure that all necessary earth straps are fitted, and that the earth strap connection points are clean and bright.

Thank Onetrack; very good points .

 

One thing though -" .... is that using the coolant either manufactured by the engine manufacturer, or the brand recommended by them is vital" 

While I would always prefer to go with the engine manufactures recommendation, this is not always possible or perhaps cost effective.

Provided you do the research ie  compare manufactures specifications, with your optional suppliers product,  you should be okay.

All to often the manufacture and or agent,has a ridiculous mark up on their recommended product, when they are the sole supplier eg Continental oil hose supplied exclusively to Rotax.