Opinions on Dex Cool Antifreeze

The Bayliner 4788 we bought last year has twin Cummins 6BTA's, 1999 vintage. The motors have 1600 hrs on them. We went through both sides of the cooling systems, sea water and closed. I replaced the green antifreeze with the orange Dex Cool premix on my mechanics recommendation. I have been reading now about a few Dex Cool crud causing horror stories. What is has been the experience here?

My son owns/runs an automotive repair shop. He made lots of money thanks to Dexcool but I think it was predominately aluminum head engines and people leaving it in for 100K miles.

Sounds like the horse has already left the barn but, If the green stuff was Fleetgaurd you could have had the Fleetgaurd tested and probably saved it. They sell test kit that have test strips for the various components of the antifreeze. My Fleetgaurd ES poly glycol was perfect after 5 years. They also sell additives to bring it back to spec. I think sticking with the Cummins Fleetgaurd make sense.
This doesnt help you but maybe someone else down the road.

The green antifreeze is fine for Cummins engines as they have cast iron exhaust manifolds unlike Yanmars which are aluminum. It is aluminum manifolds that require Dexcool antifreeze.

I doubt if Dexcool antifreeze let your son make a bunch of $ unless it wasn't changed periodically.

David

From what I have read, DexCool is one of the best coolants you can run in terms of quality for cost. Having said that, it was a miserable failure in the auto industry because GM said, "go ahead and keep it in there for life". That was a massive fail, it needs to be changed out a regular intervals just like anything else you care about. So that DexCool would sludge up pretty quick over time and wipe out thermostats, heater cores, and radiators.


I personally use green on steel only applications or red for mixed metal applications and change once a year or two depending on usage. Cheap insurance...

Dexcool is an organic acid based coolant and does not mix with ethylene glycol coolants. If you don't do a proper flush before switchover your probably going to have some cooling system problems down the road.


Via iPhone.

djmarchand said:

I doubt if Dexcool antifreeze let your son make a bunch of $ unless it wasn't changed periodically.

David

Click to expand...

You are absolutely correct that is why I mentioned that. It would eat between the head gasket and the head. Galvanic action, electrolysis, whatever.
Mostly on the V6 3100 engine (I think that was the bad one). It was a lot of labor.

I believe Cadillac had the most expensive issues because the headbolts would actually lift and allow the gasket to fail. Along with other overheating and warpage issues (guess old people don't scan the gauges at all) make that one the most expensive repair to do. Either way, GM didn't do anyone any favors by publishing that the fluid is a sealed for life one. No fluid is sealed for life except the blood that circulates through my body.

Skinny said:

No fluid is sealed for life except the blood that circulates through my body.

Click to expand...

Even then, your red cells are replaced every 120 days or so. Wish machines could heal.

I have never "lost" so much blood as working on boats....thankfully it regenerates that fast!

Quick question:
My 30 year old Perkins has the aluminum Multi-cooler. I just flushed and put in new Prestone which says "good for ALL engines". Should I be using Dex-cool?

You're way better off than the people who never change it. Something to consider next time is propylene glycol based (Peak Sierra or similar); not as harmful if some goes out your bilge pump.

Archie:

Are you sure that it is aluminum? My neighbor has 135 hp Perkins 6.354s and I am sure that the multicooler is cast iron.

But in any case I am sure that the Prestone "good for all engines" stuff is ok for aluminum. It just doesn't use the Dexcool proprietary formula.

David

djmarchand said:

Archie:

Are you sure that it is aluminum? My neighbor has 135 hp Perkins 6.354s and I am sure that the multicooler is cast iron.

But in any case I am sure that the Prestone "good for all engines" stuff is ok for aluminum. It just doesn't use the Dexcool proprietary formula.

David

Click to expand...

Thanks. Yep, a strong magnet doesnt stick to it at all. My engine manual says the "multi-cooler" was used on the T6.354 and "some" 6.354 non-turbo engines. The green stuff has been good for 30+ years so I'll stick with it.
It looks like this without the turbo:
http://www.genesisboatworks.com/thu...s/multicooler_with_turbo.jpg&w=400&h=150&q=95

All the GM technicians I know change out Dex-cool for good 'ol (green) ethylene-glycol based anti-freeze.

But, all antifreeze is not created equal. Caterpillar ELC (Extended Life Coolant) is propylene glycol based, and will with periodic testing last indefinitely.

YMMV!

Be calm and cruise on!

JS

Not replacing the anti freeze may kill your engine.

But not having the brake fluid in your car or truck changed can kill YOU!