udt vs sudt, do they mix?

[RickB]

Haven't done mine yet, so I'm not quite sure of the configuration, but I would be concerned that the vacuum method might recirculate some of the debris back off of the stainer.
I can imagine if its sucking fluid away from the hole, it might take some particles with it, and defeat the purpose of the service.

There's no good reason to think that would not happen.

 

[DiezNutz]

So, what IS the difference between diesel and gas engine anti-freeze? I've heard this before, but never explained.

Oh boy, I'm going to try to tiptoe around this one, as it's almost as bad as "what kind of oil to use" and I don't want to start a debate.

Even worse, there isn't just ONE difference, as there are a few different kinds of Diesel coolants. But in general...
Diesel antifreeze is a low or no-silicate formula, and has a more complicated package of anti-wear and anti-corrosion additives (SCAs), sometimes "pre-charged" or added separately. The biggest reason for the existence of Diesel antifreeze is a problem called "Cylinder Liner Cavitation", which you can Google to find out everything you never wanted to know about.

Since a) these smaller Kubota engines don't have cylinder sleeves we don't have to worry as much about cavitation, and b) Kubota calls for regular drain intervals, I'm not sure it's really critical to use Diesel-specific antifreeze. The only reason left, would be to have a very proper additive package.

My advice would be something like this:
1) Use Kubota's coolant, there's no guesswork and you can't really go wrong unless you don't follow the maintenance schedule.
2) Find the most compatible formulation to Kubota's coolant (guesswork), and still follow the maintenance schedule.
OR,
3) Invest in a good extended-life heavy-duty Diesel antifreeze if you have no intentions of following the maintenance schedule and/or ever draining it again.

But above all else, do not mix with tapwater/rainwater, buy pure de-I/distilled water (not spring water). Or buy pre-mixed.

 

[Chilly807]

My advice would be something like this:
1) Use Kubota's coolant, there's no guesswork and you can't really go wrong unless you don't follow the maintenance schedule.
3) Invest in a good extended-life heavy-duty Diesel antifreeze if you have no intentions of following the maintenance schedule and/or ever draining it again.

Pretty much what I'll be doing, I use their oil already so the coolant is no great leap of faith for me.

In my experience, the engine uses almost NO oil, so there's not much to be had in the way of savings by using another oil. Not much difference in price either.

A coolant change every couple years won't break the bank either.

I already use reverse osmosis/softened water to begin with, but again, a bottle or two of distilled water isn't expensive either.

Sean

 

[DZLDamon]

SCA additives are only necissary on engines with a high slenderness ratio of the cylinder walls. They don't have to necissarily be sleeved/jacketed to have this issue. The old 7.3L IDI International Harvesters found in older Ford trucks had this issue. The high compression ratio of those non turbo'd engines (21.5:1) along with extra thin cylinder walls (since they basically just bored the 6.9L out) would cause very small wiggling. When the temperature in the coolant is up, this wiggling will cause little pressure changes close to the walls. The small vacuum when the walls move away from the fluid will cause it to phase change, or flash (into steam bubbles). When the steam collapses again, it will start erroding a point hole in the same spot over and over. This is a form of cavitation.

With all that said. I doubt (at least my) smaller, overbuilt tractor block will suffer from such issues. Wall slenderness (ratio of thickness vs. length) along with high compression ratio's (which I do have) seem to add up to the issue.

However, spend the cash if you wish.