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1996 Honda Shadow VT1100-C2
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209 Posts
Discussion Starter · #1 ·
So, I'm in the auto parts store now.
They say all Prestone coolant is silicate-free.
Prestone has a few different varieties of coolant, and one is specifically for Asian vehicles that includes Hondas!

( and another type is for Toyota /Lexus asian vehicles.)

I'll go with the Asian/Honda stuff even though it's $22 a gallon for a 50/50 premix.



Based on the info here from y'all,
I won't do a "flush" with water or any
special cleaning product. Just a drain of the old stuff (which looks clean to my unaided eye when my bike overheats and pukes some up through the overflow hose...)
and a refill with new Prestone.
Bottle Fluid Shelving Drink Liquid
 

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1995 VT1100C2
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4,838 Posts
...I won't do a "flush" with water or any special cleaning product....
I agree on no "flush". Lets face it: if pressurized boiling coolant is not flushing whatever; then water from your garden hose is not going to do anything other than dilute. Some coolant remains but Honda requires changing coolant way more frequently than Prestone so the small amount remaining is not going to be a problem (much like oil change)

Oops just noticed my 2018 post above and at least I am consistent.
 

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2013 Honda Shadow Phantom 750
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4,661 Posts
So, I'm in the auto parts store now.
They say all Prestone coolant is silicate-free.
Prestone has a few different varieties of coolant, and one is specifically for Asian vehicles that includes Hondas!

( and another type is for Toyota /Lexus asian vehicles.)

I'll go with the Asian/Honda stuff even though it's $22 a gallon for a 50/50 premix.



Based on the info here from y'all,
I won't do a "flush" with water or any
special cleaning product. Just a drain of the old stuff (which looks clean to my unaided eye when my bike overheats and pukes some up through the overflow hose...)
and a refill with new Prestone. View attachment 305636
Do you not have an overflow tank on your bike?


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765 Posts
Lets agree that the goal of flushing with water is to remove any residual coolant.
I think that the biggest benefit of flushing a cooling system is that it removes solids like mineral deposits, scale, sediment, particles of corroded metal, rubber particles, and all the other foreign materials that can enter dissolved in the fluids, or from the water passages and seals breaking down. This idea is generally listed when discussing flushing. The Importance of Getting a Coolant Flush (cbac.com)

Maybe a previous owner, god forbid, even decided to add some Bars Leak because they had a loose hose clamp or used well water in an emergency?

Any coating on the INSIDE of the radiator, insulates the liquid side surface from the hot coolant, reducing cooling capacity, while physical blockage of any tubes does an even better job of reducing capacity.

That's why when I did this job for my Honda, after draining the old coolant, I removed the radiator from my machine, and suspended it upside down, to give it a vigorous reverse flow flush. I'm not concerned at all with mineral content in the flush water. It doesn't stay in the radiator, it immediately drains.

Once the radiator was dry, I spent some time straightening fins, and touching up the black paint. If air can't get through the air side passages, those areas become ineffective for convective heat flow. The thin layer of matte black paint increases radiant heat rejection, but more importantly for me, inhibits corrosion working from the outside in, something I consider important protection in this area where road salting is practiced.
 

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'97 Spirit 1100 - Chandler, AZ
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636 Posts
If I'm going to take the time to change my coolant, I'm surely going to clean AND reverse flush the system while servicing it.

As axman mentions, using a flush agent helps clean away oily residue or film that builds up on the inner surfaces during normal use.
If you feel the inside of the radiator or hoses with your finger prior to flushing, it actually feels oily/slimy/soapy.
Post flush, it feels clean and slime-free.

Once you've cleaned-out the slime, then reverse the water flow to remove trapped solids/sediment that normally won't come out if flushing in the usual water flow direction.
It takes very little time and yields good results. I pull the thermostat when doing this to get max waterflow through the block and heads.
If you don't understand how to do it, find a buddy who does to help out. Kevin🌵
 

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1995 VT1100C2
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4,838 Posts
This thread seems to have been split in 2 so I cannot see my earliest post however:
I think that the biggest benefit of flushing a cooling system is that it removes solids like mineral...
This idea is generally listed when discussing flushing. The Importance of Getting a Coolant Flush (cbac.com)...
I agree that if you are having cooling problems beyond those resolved by low coolant, fan operation, rad cap etc, then removal and thorough cleaning of the radiator or reverse flushing, may be warranted but would not consider removal necessary for typical maintenance or for the average DIY.

I read the referenced article (and a few others) and it seems to me the article is using the word "flush" as a synonym for "replace" and not as a separate task. For instance, the article does not mention a specific product for a flush and just refers to coolant. Most articles recommending "flushing" have been written by companies either selling an aftermarket "flush" product or a "flush" service (Midas, Jiffylube).

However, here is the definitive from Honda's Service policy regarding "flushes"

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