In reading through the bulletinsfrom honda, they do not mention that silicates will cause the pump to fail but it says that their coolant will lower service costs. They state that borates cause cylinder head pitting. I also note that CJH also if of the opinion that Honda water pumps last forever if run on silicate free formula. Honda also claims their coolant contains "organic" rust inhibitors which I suspect to be similar to the key ingredient in Dexcool which is also organically based.
So what's my story. In the late eighties, Honda was recommending timing belt changes at 60,000 miles. They did not specifically recommend changing the water pump as well but experienced owners knew that water pumps only last so long before they leak or seize. The route to the water pump in honda engines requires removal of the timing belt so many owners also replaced this as well.
In 1990, Honda out of the blue, recommended that timing belt changes could be extended to 90,000 miles. A whopping 50% increase same belt, same water pump. an issue comes up. My belief is that with silicate formulas, most water pumps have difficulties reaching that life easily if the cooling system is not well maintained. How many people religiously flush their systems every two years? I suspect a minority especially when their cars don't break down.
So what is significant about that? Owners were having water pump failures before timing belt changes or owners who had changed their timing belt and not change their pumps would have their pumps fail a short peruiod after their belt was changed. Timing belt removal and replacement is neither a quick nor inexpensive procedure for most japanese cars with their compact packaging. A soutce of custome dissatisfaction. Domestic engines, with their external water pumps present a different compromise.
Around this time, the organic rust inhibitors began appearing ( 1995) and was not widely deployed until 1996 by GM. So that made Honda's formula in 1994-1995 pretty much semi-exclusive.
If you look at the timing belt intervals recommended by Honda, they have been going up beyond 100,000 miles now. Nissan water pumps with many of their engines on chains, was also expensive to replace as well. Again the need for a high life pump. Toyota, I suspect face the same issues.
So for those with older Hondas who changed their coolants on a timely basis and their water pump at the time of timing belt changes, the silicate issue is not crucial. The issue of borate attacking the cylinder head was probably due to the silicates wearing out, which they do after a while, and thus not protecting the aluminum anymore.
I also found out that the switchover to DEXCOOL or organic rust inhibitors is not as "smooth" as switching over. The silicates actually ( like oil additives) bond to the metals and do not flush off immediately. In a switchover, you could get additive clashes leading to a situation and period where you get NO corrosion protection. How? in simplified form the silicate protect by covering the metal up with passive protection but the organic protection works by encouraging the metal to corrode to something that will then not corrode much more.(Rust converter like?) These actions are the opposite. So in a switchover, you MUST flush as best you possibly can and drive a lot to get that circulation going after switchover. In fact, I think it takes about 3,000 miles on a brand new engine before DEXCOOL or organic rust inhibitors to actually begin protecting. With engines that had been using silactes, it would take longer. However, silicates protect almost immediately. My suspecion is that in a switchover, it is best to flush, change to organic, and flush again and put in final refill and then drive a lot in a short period of time. Switching over is a risky thing for cars that are seldom used.
Another thing to note is that Honda does not state "long life" on their oragnic inhibitor. They probably know that while the organic rust inhibitor is longer life (35,000) it is unlikely to reliably last 100,000 or 150,000 miles.
DEXCOOL must be applied in a 50/50 mix. If used too diluted or concentrated, problems will occur. this is the same case for silicate formulas too but it appears to be more critical for DEXCOOL. That probably explains why Honda coolant is only available PREMIXED only. That way, they control the concentration. They recognize that many people pour the jug of coolant in and then top up with water leading to too concentrated mixes many times.
Another issue which comes up is that there is conflicting data regarding the "roughness" of silicates. I have found information that states that only when the silicated antifreeze is worn out, overboils or needs changing, then the silicates come out of solution and begin to be abrasive. this is unlikely to happen in well maintained cooling systems.
For me, since I currently don't put a lot of miles anymore on my 14 year old Legend, I am caught in between. I think I'll just maintain the pattern I've been on for 12 years and if my pump begins to leak before my timing belt changed is due, then I'll change both at the same time. However, after that, I'll just have to risk the crossover.
I apoogize for this long post but I'm sure it helps folks out.
looking at a bottle of it now its says mineral enriched or somthing.
