OK, here is what I learned. Cold start is so much better than with normal diesel. Needs half a turn, when with normal diesel my engine starts with 2-3 turns. I took all old fuel out and used pure HVO, did not mix, to see the difference. But it was not perfect. Something in engine did not agree with HVO and engine RPMs sometimes went up and down and when I wanted to throttel for max RPMs, it usually did not happen, stayed in "cruising" RPMs and maybe after few minutes running it reached full RPMs and then slowed down again. Same RPM problem with half throttel. But engine never died and in fast idle (RPM when the "pounding" just stops) it was stable. And when I put old diesel on top of HVO (new mix was more regular diesel than HVO) problem was gone. So it was either a coincidence and I had a debris in fuel line from pulling all old diesel with wet vacuum cleaner that eighter dissolved in regular diesel or came loose just when i switched back, or fuel pump did not like HVO different viscosity or someting in HVO does not agree with my fuel filter (it is not yanmar original)

Edit: Fuel used was Neste MY

Yeah, FAME and HVO are different liquids even outcome is diesel. FAME ties water and as such is a petridish for bacterial growth, HVO does not.

Go for it! Let us know how it went. :D

But seriously, I have considered doing the same. What's the worst thing that can happen?

My research also came in conclusion that HVO is even more resistant to diesel bug than regular diesel (witch in EU probably always has some % of FAME in it)
Also the guy with Volvo Penta MD7, said that after owning his boat for 5 years (4 using HVO) he looked into fuel tank and it was clean.
What I have found out so far is that HVO is supposedly a little bit less viscous, so some sensors might get different reading because of that. Should not be a problem for 1GM tho. Since it only has a temp sensor and oil pressure sensor. What I have not found is definitive answer how the lubricity compares to regular diesel.
For environmental cause, HVO might be not as great as advertised. According to one of Estonian fuel distributor that does not sell HVO, energy that goes into refining HVO does not justify cleaner emissions from exhaust (however all this should be taken with a grain of salt. There is a lot of misinformation about these kinds of topics. Take electric cars and their environmental impact for example). But that is probably not a reason most of us boaters would be using this fuel anyway. Driving a car, you will never breath your own emission gases, but its not always a case on a boat. I personally want to get rid of diesel smell. I have even considered converting to electric motor, but it is too expensive for my taste, I prefer investing 5k rather into new sails.
So my plan, when I make the switch, is to properly clean my engine and engine room and hope for the best.

I'm not trying to outright dispute Panu, but would rather like to ask some additional information regarding HVO and bacterial growth etc.

According to for example these sources:

https://www.crownoil.co.uk/guides/diesel-bug-contamination-guide/

https://content.pon-cat.com/en/differences-between-fame-and-hvo

...HVO is not considered a "biofuel" in the same way as FAME. But I'll be glad to admit that I'm not an expert when it comes to fuels so if someone wants to correct me, go ahead.

Since this is quite an important topic as to the use of HVO, I think it is worth discussing thoroughly.

[quote=Ülari post_id=35672 time=1719143444 user_id=431]
Has anybody used HVO (Hydrotreated Vegetable Oil) diesel with original Yanmar 1gm engines? It is supposed to burn much cleaner and therefore be better for engine and also less smoke from exhaust. [/quote]

Tervehdys

All biofuels are biodegradable and that means in practice that it has a natural negative tendency for getting bacteria, fungi or yeast infections, especiallay when that bio fuel is close contact with water. Anaerobic bacterias will have a terrible smell (smells like urine #-o) when fuel is infected by germs, Fungi and yeast will also generate death sponge / mushroom like biomass into fuel tank that could easily clocked any fuel filters and fuelhose connections,not to mention fuel injectors.

I have worked with metalworking fluids past some 30 years. Water michible coolants (metalworking fluids (MWF) are basic oil + many kind of additives mixed with emulgators, bactericides and fungicides. Those products are designed to be used in such kind watery environment and I happened to know that in the worst cases some MWFs needs to be changed max upto 4 to 5 times a year. bio-degradeable fuel is not desingned into that challenged environment. "Diesel bug" is a well known problem at warmer environment amongth the bluerwater cruisers. EU's directives to add more and more bio components into our diesel fuel has brought this warmer climate's problem into our "nordic environment" too...? =D>

Water + bioabegradeable oil will be a certain promblem collector. I would keep it as far away of mý boat's fuel system as I ever could. [-X

It can be mixed in any ratio. So no problem adding it to regular diesel (or vice versa). But I will probably pump out old diesel from tank and also clean water separator, since it should be cleaned once a year anyway. I can use old diesel in my heater.
Only reason I want to put pure HVO into empty tank is to actually see, hear and smell the difference, if there is any.

In Estonian sailing FB group, somebody has used HVO for 4 years on Volvo Penta MD7 without issues. Nobody with yanmar tho.

AFAIK a 1GM10 made today is exactly the same engine as it has always been. And the only difference between the 1GM and the 1GM10 is that the piston is sligthly larger on the 1GM10. I can't find any negatives either. One additional benefit would seem to be a longer shelf life (which in a sailboat might be a relevant factor) and immunity to diesel bacteria.

So I'd be tempted to switch to HVO also after using up all of the diesel in the tank/canisters. That might take a while though with our usual consumption. :)

I found that too, but is 1GM produced in 80s same as 1GM-s produced now?
But that probably does not matter. I cant find any reason HVO cant be used in any diesel engine. So I will probably try it. Only negative side (besides higher price) is that I cant get it in any marina. Must haul it on boat in canisters, but considering it does not smell, canister trip to gas station that has it, should not be a problem.

A very interesting topic indeed.

A quick search found this:

https://www.yanmar.com/marine/about-us/yanmar-marine-international/news/yanmars-sail-and-powerboat-engines-approved-for-hvo-fuels/

1GM-series is mentioned so I guess it's just a matter of taking the plunge.

Has anybody used HVO (Hydrotreated Vegetable Oil) diesel with original Yanmar 1gm engines? It is supposed to burn much cleaner and therefore be better for engine and also less smoke from exhaust. It is about 15% more expensive than regular diesel, but considering sailboat does not use much fuel, it might be worth a try.
Best part is that it does not smell.