Anti-Freeze

[MickeyMiller]

I picked up what I thought was 8 gallons of pre-mixed anti-freeze from a Cummions dealer in preparation for my 100K maintenance. When I got home, I found that I actually had:

- 4 Gallons of Propylene Glycol Concentrate (which = 8 gallons of anti-freeze)

- 4 Gallons of Ethylene Glycol 50/50 Premix

Questions:

1. Is there a preference for Propylene Glycol vs. Ethylene Glycol?

2. Are Propylene Glycol and Ethylene Glycol compatable?



Mickey

 

[DavidC]

Go here and call customer assistance to get the true answer and expertise. I have called before and they are very helpful.

Customer Assistance



Dave

 

[MickeyMiller]

Dave,

Thanks for the suggestion and quick response! I just e-mailed Customer Assistance... I will post their response.

Mickey



... got to learn to spell Cummins, got to learn to spell Cummins, got to learn to spell Cummins, got to learn to spell Cummins, got to learn to spell Cummins

 

[rbattelle]

I've been running Fleetguard Compleat ES PG for over 3 years now with no problems at all.

I originally wanted EG; the knuckleheads at the local Cummins Bridgeway put PG in there. Note the manuals on these trucks specifically prohibit the use of PG. When I confronted the Cummins shop on this, they replied that PG is what they put in all their engines, and it wouldn't be a problem.

3 years later, and so far they're right. I have added a small amount (about 1 pint) of the extender chemical over the past 3 years. It's supposed to be added every 150k miles or 1 year, whichever comes first. Personally, for a 7-gallon coolant system on a personal truck that runs fewer than 20k per year, I think it's totally unnecessary to add the chemical every year.

This coolant is supposed to be good until the first engine rebuild. I'll probably go ahead and change it out around 500k.

I've never been able to figure out why Dodge doesn't want PG in the engine, while Cummins says it's fine. My theory is that Dodge was afraid the PG would interact with the EG-based HOAT coolant that comes from the factory. But Fleetguard assured me that the Compleat PG has no known chemical incompatibilities with any coolant on the market.

PG has slightly less cooling/anti-freeze capacity than EG (the boiling point is a little lower, and the freezing point is a little higher). We're talking about just a few degrees on each end. But PG is much less toxic, which is why it's offered - as a safer alternative to EG. As far as I know, the two are okay to mix.

In a 50/50 mix, PG freezes at -27°F and boils at 222°F (at standard pressure - note the boil point will actually be well above 240°F assuming a 16psi cooling system).

At the same conditions, EG freezes at -34°F and boils at 226°F.

Back when I had the coolant changed, I ran the calculations for the boil margin on these cooling systems. Plain, ordinary distilled water won't boil at 16psi until above ~245°F, IIRC. Maybe Dodge didn't bother to make any calculations, and simply assumed that the slightly lower boil margin on the PG mix would be a problem in trucks towing large loads over mountainous terrain.

Ryan

 

[MickeyMiller]

Ryan,



As usual, your information is spot on! Here is the response I got back from Cummins:



Propylene Glycol and Ethylene Glycol are compatible. The main difference in the two coolants (antifreeze with additives to protect against liner pitting and corrosion in your cooling system) is that the Propylene Glycol coolant is more environmentally friendly, can be used in food service and marine applications and some states require it's use. The Propylene Glycol has a freeze point of -27 degrees Fahrenheit and the Ethylene Glycol has a freeze point of -34 degrees Fahrenheit. The two glycols can be mixed with the only issue that you will not be able to determine your freeze point correctly.



Mickey

 

[FourBarR]

I have used Shell ELC since my truck was new. Now have 450,000kms with zero problems. Shell claims 1,000,000 kms or 600,000 miles then add addative to the 1,000,000kms.