[C320-list] Which coolant for Yanmar 3YM30 in Australia?

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David Hayes

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Apr 9, 2022, 7:21:13 AM4/9/22
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Hi all,
I’ve decided to take over the regular engine servicing and would be grateful if any other Aussie owners out there can tell me which coolant to use - the Havoline product recommended in the service manual is not readily available and I am getting conflicting advice from local retail outlets regarding which product I should use. The coolant in the boat now is green/blue.
Any feedback appreciated!

Regards, David Hayes
2006 Harlequin

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David Hayes
Mobile: 0478 956 056<tel:0478%20956%20056>
20 Cooks Outlet Road
Loch Vic 3945

Joe M

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Apr 9, 2022, 8:12:00 AM4/9/22
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I use yanmar. It is premix 50/50 and red.

sail-ability sail-ability

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Apr 9, 2022, 11:08:30 AM4/9/22
to Joe M, C320...@catalina320.com
Any of the Prestone new antifreezes are compatible with the engine
metals. I use the premix as it's easier to use. These products are
lifetime limited so every other year, I drain the engine coolant from
the spigots designed for this and refill the engine. This is not a
complete coolant change as there is still 4L or so in the hot water
heater. Draining the hot water heater is a bit of a mess and not
required. Adding fresh coolant to the engine every other year or so,
works to keep good coolant in the system.
Regards
JohnM
1999#574


------ Original Message ------
From: smith.b...@gmail.com
To: C320...@catalina320.com
Sent: Saturday, April 9, 2022 8:11 AM
Subject: Re: [C320-list] Which coolant for Yanmar 3YM30 in
Australia?

I use yanmar. It is premix 50/50 and red.

On Sat, Apr 9, 2022 at 7:21 AM David Hayes <david...@hotmail.com>
wrote:

>

David Prudden

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Apr 9, 2022, 3:44:59 PM4/9/22
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Just be sure to avoid mixing the newer orange antifreeze with green antifreeze. When mixed, they tend to turn to sludge and won’t circulate. The orange is a newer technology, meant to help avoid corrosion in aluminum and copper engine parts.

David Prudden
Teachers Pet II
2001 #787

Sent from my iPhone

> On Apr 9, 2022, at 11:08 AM, sail-ability sail-ability <sail-a...@sympatico.ca> wrote:
>
> Any of the Prestone new antifreezes are compatible with the engine metals. I use the premix as it's easier to use. These products are lifetime limited so every other year, I drain the engine coolant from the spigots designed for this and refill the engine. This is not a complete coolant change as there is still 4L or so in the hot water heater. Draining the hot water heater is a bit of a mess and not required. Adding fresh coolant to the engine every other year or so, works to keep good coolant in the system.

Jeff Hare

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Apr 9, 2022, 3:52:44 PM4/9/22
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If it's an option and available, it's a good idea to only use the Yanmar (or
Yanmar approved) antifreeze. The Approved yanmar coolant is RED. Not green
as it was way back. They don't approve of the green in their engines
anymore as they discovered something they didn't like.

If you mix antifreezes you may end up with slime coating the inside of your
engine coolant paths. Caused when the additives react and settle out of the
solution.

If you take off the radiator cap and wipe your finger inside and it feels
really slimy, it may possibly mean that there has been a change in
antifreeze type at some point in the past (or it's just really old). I'm not
sure but I think only a chem flush can get rid of that completely.

That's why I think the best option (long term) is to try to get back to the
stock Yanmar antifreeze properly. Then the maintenance is quite easy. It's
a few dollars more money than the stuff available in auto and department
stores but it's not like most owners need to do this very often.

Note: Some brands say that they're "compatible" with other brands. That may
be a stretch (or not). But it may also be that their *own* additives won't
break down or settle out. It doesn't necessarily mean that what's left of
the *other* antifreeze won't react and break down and cause slime. It's not
super easy to fully drain all the old antifreeze in these engines because of
the hot water heater (need to remove the thermostat for sure).

If you can swing it, have him fully flush it out with fresh water and put
the Red Yanmar coolant in. Then every few years, you can gravity drain out
whatever flows out easily from the engine side drain ports and top off with
the Yanmar Red.

-Jeff H.
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