Type of coolant used in 912

“Rotax recommends flushing the system annually or at 200 hours.”

Reference please. What engine do you have? Is there a Service Bulletin I missed?
The 912 MML Edition 4 dated July 1 2021 has no such recommendation. For the circumstances listed where a flush is required, those instructions are found in Para 12-20-00.

Jim Isaacs wrote:

“Rotax recommends flushing the system annually or at 200 hours.”

Reference please. What engine do you have? Is there a Service Bulletin I missed?
The 912 MML Edition 4 dated July 1 2021 has no such recommendation. For the circumstances listed where a flush is required, those instructions are found in Para 12-20-00.

Hay Jim - who's words are you quoting?

FYI - Flushing of the cooling system should not be required, (if using modern coolant meeting Rotax specifications), when the same brand & type of coolant  is used to replace the old, within 2 years/200 hrs of operation (my opinion & experience).

Flushing should be done if changing brands and or type of coolant OR if you suspect the coolant has been in service for much longer than 2 years.

I believe the Rotax coolant specification to be based on European automotive standards for modern mixed metal cooling systems 

'NOTE: Coolant should be a low silicate and nitrite free formula. Follow coolant manufacturer directions regarding mixture percentages etc.. Coolants with a mixture of 50% antifreeze and 50% of distilled water recommended by the authorized distributors (not tested from BRP-Rotax)'.

Hi Sean,

I’m quoting the first post made by Dennis. I can’t find any Rotax service instruction or maintenance manual recommending coolant changes based upon time or hours in service.

Jim Isaacs wrote:

Hi Sean,

I’m quoting the first post made by Dennis. I can’t find any Rotax service instruction or maintenance manual recommending coolant changes based upon time or hours in service.

You are correct - my mistake.

As for coolant changes - I base my schedule on about 50 years of servicing my own vehicles and equipment and observation of my results compared with many others.

I have found that replacing the coolant, at about the intervals I suggest (without flushing & using quality materials), results in clean, (no deposits/residue, corrosion - pitting - cavitation, evidence of electrolysis) of the cooling system interior. So I follow the same practise with my Rotax and so far (10-12 years) so good.

The Rotax cooling system only takes about 3-4 litres of coolant (depending on installation) so the cost of replacement is minimal, even with the best quality of materials.

Note: This is not a scientific position and I have never completely dismantled (destruction testing/investigation) a cooling system to see if my theory is 100% correct. I have inspected radiator cores from the fill/top & bottom pipes, interior of hoses & thermostat's, never had a pin hole, blockage or "boiled" a cooling system. 

No worries! I was hoping by now Dennis could confirm where that requirement came from.