Coolant Info -- C-355
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Diane
Feb 7, 2026, 5:29:31 PM (13 days ago) Feb 7
to C-355 Google Group
Which coolant?
According to Richard Mastry, with Mastry Engines, Catalina's supplier of all Yanmar engines:
The engines use Yanmar Ultralife YG30.
The recommended alternatives are all pre-mixed:
Texaco LLC part #7998
Havoline LLC part #7994
These are also listed in the Engine manual. Although he did not explicitly say that you should flush out the Yanmar coolant to use the other approved brands, he recommended it. I believe the other two brands are also red in color. Interestingly enough, here in the Northeast it has been equally difficult for me to find either the Texaco or Havoline brands.
Finally, I buy all of my Yanmar spares from Old Port Marine in Newport RI. I greatly respect their advice and expertise and asked what they used. For their launches, rebuilds and repowers they use Shell Rotella TELC Red 50/50. I will probably go with this if and when I can no longer get access to the Yanmar stuff (which is surely rebranded from someone else)....
Amazing that something as simple as which coolant to use can be so
complicated! ~ Jon Vez
When asked about flushing the coolant, Jon explained:
As for flushing, yes using distilled water until you can get 90% of the old out, then refill with what you are going to use, drain and refill should do it (a royal pain, which is why I did all the research before in the first place). You will find that the hardest part is getting the old stuff out of the hoses leading to the hot water heater. You can disconnect those hoses at the heater and try to drain as much as you can from there. Finally you will probably have the airlock problem rearing its ugly head again. For this, just keep filling and vacating air bubbles. Some folks crack the hose at the water heater and try to burp out the air. I find that the low coolant drain is ideally situated to get most of the air out with relative ease...good luck and I've confused you in any of this, let me know and I will try to clarify...
According to Richard Mastry, with Mastry Engines, Catalina's supplier of all Yanmar engines:
The engines use Yanmar Ultralife YG30.
The recommended alternatives are all pre-mixed:
Texaco LLC part #7998
Havoline LLC part #7994
These are also listed in the Engine manual. Although he did not explicitly say that you should flush out the Yanmar coolant to use the other approved brands, he recommended it. I believe the other two brands are also red in color. Interestingly enough, here in the Northeast it has been equally difficult for me to find either the Texaco or Havoline brands.
Finally, I buy all of my Yanmar spares from Old Port Marine in Newport RI. I greatly respect their advice and expertise and asked what they used. For their launches, rebuilds and repowers they use Shell Rotella TELC Red 50/50. I will probably go with this if and when I can no longer get access to the Yanmar stuff (which is surely rebranded from someone else)....
Amazing that something as simple as which coolant to use can be so
complicated! ~ Jon Vez
When asked about flushing the coolant, Jon explained:
As for flushing, yes using distilled water until you can get 90% of the old out, then refill with what you are going to use, drain and refill should do it (a royal pain, which is why I did all the research before in the first place). You will find that the hardest part is getting the old stuff out of the hoses leading to the hot water heater. You can disconnect those hoses at the heater and try to drain as much as you can from there. Finally you will probably have the airlock problem rearing its ugly head again. For this, just keep filling and vacating air bubbles. Some folks crack the hose at the water heater and try to burp out the air. I find that the low coolant drain is ideally situated to get most of the air out with relative ease...good luck and I've confused you in any of this, let me know and I will try to clarify...
Jon Vez
Feb 8, 2026, 8:34:48 AM (13 days ago) Feb 8
to catal...@googlegroups.com, Google Group C-355
Diane,
Thanks so much for making sure the institutional knowledge of this great boat is being preserved.
Brings back memories of sharing knowledge with those of us early adopters. It’s a bit scary jumping into a new design, but having others to share the experiences is priceless. The conversations with Eddie were priceless and reassuring knowing we weren’t alone.
I firmly believe the 355 was a perfect design for cruising in comfort with a boat that is great to sail.
I don’t know who this Jon Vez character is, but so glad Jeff Hare (who with Shelly) is the current caretaker of Solstice and is willing to keep the learned experiences alive for current and future owners.
Fair Winds
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Walter Baransky
Feb 8, 2026, 11:12:48 AM (13 days ago) Feb 8
to catal...@googlegroups.com, Google Group C-355
To view this discussion visit https://groups.google.com/d/msgid/catalina355/7D3C3FE8-728C-4D53-9B1E-BCC2E61D8F90%40gmail.com.
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