SI Selection of Operating Fluids

Hi Byron,

The Penrite would seem to have much the same qualities/specification as the Castrol SF that I use - my guess its oaky to use in your Rotax.

FYI Mercedes Benz OM coolant was (possibly still is) blue.

The colour has no bearing on the suitability of the product for use in your engine however most European engine compatible coolants are now Red/Orange

Hi all in Australia

Currently the Rotax distribution system, and with it the support system, is going into a changeover phase.  Give it a few weeks and you will see some new support plans for your region.  What can help is try to find out what CASA approves for fuels, to what standards, for both auto fuels you use and if they will allow the newer unleaded Avgas formulas.  For example AVGAS 100 LL is under ASTM D910.  In searching this after some online chat with the forum it seems very complex for some reason for auto fuels.  RON is used by CASA as a reference but that is a test method and not a standard.  Perhaps I just cant read the CASA webpage correctly. 

Coolants are not covered under CASA, so In general to get a coolant on the Rotax listing requires input from the regional area distributor.  Currently the best are HOAT or OAT fluids.  What will help is actual verification of the fluid performance in field use with some documented time on the fluid.  Normally that is done by the distributor of the region.  If you had fluids that were recommended in the past but you do not see them listed such as the Castol that would be a good start.  Sean is correct in that the color is marketing and not performance.  The materials safety data, MSD, sheets do tell the story of what the makeup of the fluid is.  Availability in your region is paramount for sure. 

About Mercedes coolants, they actually have 2, one is blue and one is pink.  We all know that Mercedes does not make coolant so this is a private label product.  What you need to do is get the material data sheet and confirm what it is.  Generally any newer coolant will be an HOAT or OAT fluid these days.  Avoid fluids that have silicates or phosphates.  (some HOAT fluids have tiny amounts of additives but they are not enough to cause issue) Normally all the fluids today have long life.  OAT fluids usually are 5 year and that fits nicely with our 5 year requirement for hose/rubber changes.  HOAT fluids in many cases are now 6 year due to the improved formulas.  I personally would not mix fluids, even if the coolant producer says you can. 

Cheers

Long time lurker, first time poster here:

Automotive petrol (i.e. gasoline) standards in Australia are defined at the federal level (some states have more restrictive standards) by the Fuel Quality Standards (Petrol) Determination 2019. Typically available grades are 91 RON Unleaded , 95 RON Unleaded, 98 RON Unleaded and E10 Unleaded. (E10 has a defined minimum RON of 91, although many suppliers' product has a higher rating) In some remote parts of the country, in order to combat substance abuse ('petrol sniffing'), standard 91 RON ULP is replaced with a "Low Aromatic" fuel blend sometimes known as "Opal" fuel.

To the best of my knowledge, CASA does not actually set any particular specifications for aviation fuel; it is the pilot and operator's responsibility to ensure that the approved type and grade of fuel is used. This is usually the grade/s specified in the aircraft's flight manual. (Under CASR 91.095, as modified by section 21 of CASA EX81/21, any reqirements and limitations in the AFM have the force of law.) As a practical matter, every fuel supplier I was able to obtain a datasheet from says that their AVGAS complies with the latest issue of ASTM D910.

Other guidance on the matter of fuel grades from CASA includes

•  Section 3 of Advisory Circular 91-25
•  GM 91.465 in Part 91 AMC/GM

For coolant, I use the standard (green) Castrol Radicool; It's what my late L2 always used and recommended.

Hi Tim and all

Thank you for your explanation of the Australian conditions from CASA.  That explains the way they post the data on fuels.  it is rather odd they decided to not simply give the fuel specifications as most other countries.    it kind of leaves you with the concept of using tribal knowledge however in what you use I think.  it does explain why there are no fuels listed on the Rotax Fluids Service Instruction I guess.  

I did pull up the specs on the coolant you noted and find it is a base type of coolant.  The issue with these fluids in that the green fluids are made with inorganic materials (inorganic acid technology, IAT) and tend to be electrialy more conductive.  This over time, for people who do not change the fluid regularly,, will lead to corrosion from electrical discharge as the fluid moves in the engine.  You can actually test this with a good digital multimeter.  (lots of info on the web on this one) The major shift is coolants in the past 20 years has been to organic acid technology. (OAT fluids).  In the past few years they have improved on those to hybrid fluids, HOAT, that include some specialized additives.  These are made to have no electrical activity and therefore avoid the electrical discharges inside the cooling system. (electrochemical discharge, ECD) Hoses that have been on engines where this occurs will crack from the inside to outside.  If you do switch you must be very careful to fully purge all the old fluids from the system and not mix the coolants. 

Naturally you can do what you want, just my suggestion. I love the new coolants nowadays.