Okay I'll bite - what's wrong with Dex-Cool?
Steve my 2003 Westerbeke had some rusty sludge issues and only ever had Dex-Cool used. It was never, ever mixed and it was changed regularly since new every two seasons.
You never know until you look or have an issue.. My engine was currently cooling fine but was well on her way to not cooling well.
I do not bring this up to tell you what you should do with your own engine. I bring it up in the hopes that some will do more research beyond what the engine manufacturers say to do. GM is still putting Dex-Cool in cars & trucks while at the same time paying out hundreds of millions in damages from the Dex-Cool suit.
Here is an interesting point to consider:
Originally Posted by Enviro Tech Chemical Inc.
As long-lived as OAT-based antifreezes are, GM does not recommend using Dex-Cool in older vehicles with copper/brass radiators and high lead solder seams. The reason is that the additives in Dex-Cool can eat away at the solder, leading to premature radiator failure. There is also concern that it can erode water pump impellers that experience a lot of cavitations. (New GM engines have specially designed water pump impellers to minimize cavitations).
Originally Posted by Hemmings Motor News
Can you run organic coolant in an earlier vehicle? Yes and no. OAT will work if your radiator is aluminum and you flush your entire cooling system with water and completely refill with OAT, but there are some issues with the interaction between organic coolants and lead solder, so using OAT in a copper radiator is not recommended.
Of course the makers of Dex-Cool insist it is safe for copper radiators & HX's...?? Who to believe is up to you guys..
Boats use copper heat exchangers which are generally soldered together with a tin/lead solder and they some times mix aluminum in there too. Again I have done my own research, and know my own experience with Dex-Cool, I only post this as a beginning point for your own research..
Unfortunately we'll never know the real cause of these issues because GM took the easy way out and chose to settle instead of fighting this or taking this to court so we would all finally know what the real issue and answer is. With settlements, they avoided lots of potential liability by covering only "named" issues. These "named issues" BTW do not include marine engines..
My engine was still running cool but was developing the all too common Dex-Cool sludge in the HX and engine. I think we'll eventually begin to see more issues especially with engines using copper HX's that are brazed with solder..
I spent a long time talking about this issue with a guy who makes this his profession. He showed me piles and piles of parts he claimed were destroyed by Dex-Cool and a 2007 automobile sitting in his shop that he was converting back to global. This was a car owned by the wife of a guy who had GM / Dex-Cool head gasket failures. Paul even showed me the test strip on that 2007 and it was highly acidic. This car had less than 50k and was less than two years old. Dex-Cool claims 5 years or 150k.... there is NO WAY it should have been that acidic..
One of my problems with Dex-Cool is that it is sooo finicky. It does not like air or systems with low water, it does not like any sort of other antifreeze, it does not like some solders, copper, brass etc. etc.. There are literally millions of vehicles affected by these issues I don't see why marine engines would be immune, mine was not. Green or global antifreeze is no panacea in a diesel, and it needs to be changed on a regular basis, but my engine still got switched to an HD coolant for diesels.
This was the cleaner of the two ends of my HX. Unfortunately taking a picture into a tube is tough and the other end did not come out as well (to dark). As I said still cooling but for how long..? The sealed side of a cooling system should not look like that especially after having been changed by the PO with brand name Dex-Cool every two season since new in 2003..
If your own research leads you to a conclusion to stick with Dex-Cool that is all that matters as your own personal comfort surrounding your engine is paramount.
Some more reading:
ConsumerAffairs.com / Dex-Cool
DEX-COOL Class Action (LINK)
DEX-COOL Class Action (LINK)
GM Owners Steaming Over Dex-Cool (LINK)
San Carlos Radiator Specializing In Fixing Dex-Cool Issues (LINK)