Prestone LowTox + cooling system flush

My experience is that any rad flush that comes in a can is a waste of money! Not that they probably don't work, its just that were does all the crap go that you are trying to flush out? Usually it just piles up in a low spot somewhere. The only way to get it out is to have your system power reverse flushed where they do the block, heater core and rad all seperate, and they actualy flush everything out(nothing left in the cooling system). Also make sure you get a antifreeze tester that works for propelene antifreeze as they rate differently for freeze protection

Why the Prestone LowTox? Have you verified with Prestone that it's "compatible"? The much discussed water pump/antifreeze compatibility is the important issue here. I prefer to play it safe and use the Honda coolant, currently the Type 2 which is premixed.

That's a kinda risky thing to do IMO - leave the thing running for 30mins during the critical period of air bleeding from a freshly refilled system.

It depends on the ambient temp of course but my only experience is that I know when it was 15F and I idled my already warmed up engine with the heater on 3/4 heat and fan on position 1, the temp gauge showed a drop in a few minutes.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

I used to use Havoline DexCool, which doesn't contain any of the nasties that are supposedly verboten in Honda cooling systems.

Nothing bad seems to have happened. What's the preferred procedure? Would it be to let the thing run for a few minutes, let it cool, and do so repeatedly. I'm pretty sure no shop would ever go to those lengths, although a DIYer might not care about the time.

It was maybe 55F, and the hood was open.

Well - it was sitting in the garage for quite a while, so it was pretty much already paid for. :-)

Sure. However - it's supposed to clear out a certain amount of scale that builds up in the radiator. That wasn't a problem for me, since I had the radiator replaced last month. I was using Bars Leak to try to seal off the rad leak until I could get it fixed or replaced.

Before this weekend, I'd only done a drain and replace at 30K miles and every 15K miles after that. I was told it might have been excessive. The flush did seem to get out some of the crap, and it seemed to be fairly well suspended when I drained it about 40 min, when the system was warm to the touch. I removed the rad cap with a wet towel, and there was a slight hissing sound.

I believe your '95 GSR is like my '99 GS, in that Honda had eliminated the air bleed screw from those models, which makes it a little more difficult to get all the air out. I usually warm the engine up and blip the throttle a few times, which causes belches of air to come out of the radiator filler hole.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

No - there's an air bleed screw right on the thermostat housing. It has a 12mm 6-pt head with an outlet in the middle. There was a small hiss before coolant ran out in a stream. Then I topped off the coolant.

I used that dex cool also. I mixed it 50/50 outside the car with distilled water. I don't have any time or mileage on the car to speak of since then so I have no idea if anything "BAD" is happening as a result of using this stuff. All I know is the the friggen Honda dealership wants $11.99 a gallon of 50/50 premixed antifreeze. That is a god damned rip off at $24 a gallon plus tax. That is just blatant BS, and they don't even use the Honda coolant when they do your flush.

CaptainKrunch

Unless Preston has changed the compound, thier low tox antifreeze has silicates that can cause early water pump failure. Terry

I'd like to find out. The only Prestone product I'm sure doesn't contain silicates is their extended-life coolant. If it had silicates, it wouldn't meet the GM standard for Dex-Cool. The shop that replaced my radiator said they used regular Prestone in the yellow bottle, although they gave me the option of Honda Type 2 coolant if I really insisted on paying $20 more. This was one of the most trusted shops in my area, and they seemed to think the alleged problem with silicates is way overblown.

I recall that these extended life coolants are supposed to form some sort of waxy protective layer. Silicates are mildly abrasive, and will supposedly wear away at or prevent the layer from forming.

I can assure that the silicate issue with Honda water pumps is not overblown - I've seen the results: badly binding water pump after ~20K miles.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

Mixing different types of coolant in a car is usually not a good idea.

You said it George. These boys need to do a little more research on coolants, their ingredients, and their proper application. Until then they really should stick with the manufacturer's recommendation. (After research they'll know better and they'll stick with the manufacturer's recommendation)

But, I'm sure they'll ignore us and use Dexcool, or prestone green, or RV antifreeeze, or maybe mix them all, 'cause some guy they know said it was OK.

I know. However - just topping one ounce of the radiator is unlikely to cause a problem. My primary concern is that Honda coolant is silicate-free and that's the most important thing for a car still under warranty. OEMs change their suppliers and formulas all the time - I know the US supplier for Honda "Type I" coolant must have changed at least once.

The one thing that should be avoided is anything containing silicates with factory installed extended-life coolant. Prestone says 10% is enough to bring the change period to 1-2 years. Take it for what it's worth, but Prestone also claims that they've tested their extended life (Dex-Cool) coolant for compatibility with Honda coolant.

Does anyone use Redline WaterWetter? I remember seeing some spec sheet (may have been for the dry version) that said it had silicates.

I can understand where you're coming from. However - right now people are using Honda Type II coolant in systems that were installed with the non-extended-life coolants, if only because American Honda has discontinued their original green stuff. Has anyone really verified the compatibility of this combination?

I've seen this stuff at AutoZone. Still - the consensus seems to be that silicates are to be avoided at all costs. I'll probably change my coolant one more time - maybe with two flushes of water to get out as much of the Prestone LowTox as possible.

I used Dex-Cool in my system because my coolant hose burst, I happened to have it in my garage, and there was no way I was going to find a place that sold Honda coolant at 8PM to fill the system. I think Honda also switched to "Type II" by then". Since then (about 17K miles), the only bad thing that happened is that the radiator tank cracked, which can't be attributed to the coolant. My mechanic even said he was surprised it lasted that long (130K miles).

However - in all its infinite wisdom, Honda only sells the Type II coolant 50/50 premixed with water. This isn't very helpful for someone who wants to flush out a system (i.e. moi), or lives in sub-freezing climates. I can imagine someone topping off coolant with whatever is available in an emergency, and wanting to do a flush as soon as possible.

|However - in all its infinite wisdom, Honda only sells the Type II |coolant 50/50 premixed with water. This isn't very helpful for |someone who wants to flush out a system (i.e. moi), or lives in |sub-freezing climates.

I don't understand this. The lowest freeze point is reached at 50/50 mix. Rex in Fort Worth

No, the lowest freezing point is at somewhat stronger concentrations; see for example:

The service life of Honda Type 2 is double the old Type 1 so there's really no increase in cost at all. I believe that they are doing the premix because many people do not realize the potential damage which can occur with mixing with just tap-water.

Dexcool is bad news - I'd get it the hell out of my car, based on the class action suit and others' experiences:

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

Then again it might be a bad fit and the results are kinda painful. Here's a (quite old) article on it:

Itsays that G-05 is "moderately silicated." I wouldn't take the risk. I'llstick with the Honda stuff.

Did you know there's a class action suit on Dexcool?... read about it in the links at

It's not just radiator andheater cores which are sprouting leaks - head and other gaskets too. Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??