Mix green and brown antifreeze?

[Zen Road Warrior]

My engine has the old and familiar green antifreeze. Can only seem to find the new brownish antifreeze at the shops/stores/truck stops. Is it okay to mix these?
thanks

[TheBigR]

No I don't beieve it is recomended. If it was my truck I would test the anti freeze in it now. If it ok use it, but eventually change over to the extended life anti freeze. Which is the brown anti freeze. Anti freeze is one place I don't cut corners, can be very expensive if you let it go! A diesel engine has a lot of internal vibrations which will cause pitting if anti freeze is bad.

[RebelDarlin]

From here: http://www.eetcorp.com/antifreeze/antifreeze-faq.htm#q8


Can I add propylene glycol based antifreeze to my existing ethylene glycol based antifreeze?

Ethylene glycol and propylene glycol are chemically very similar and can be mixed without harming the cooling system. Ethylene glycol does have better heat transfer properties than propylene glycol. Adding propylene glycol does not make the ethylene glycol less toxic.

And From here: http://www.universallubes.com/0703-1-AF-Rainbow.pdf


Heavy Duty – Diesel Engines
Diesel engine antifreeze/coolants are formulated for longer and more severe operation
than those formulated for light duty engines (of course, these higher performance
coolants can be used in light and medium duty applications). Heavy duty diesels, and
some light and medium duty diesel engines, are subjected to cavitation erosion
problems, as well as the corrosion and water pump durability problems shared by all
engines.
The colors of common U.S. heavy duty antifreeze coolants are:
_ Red-orange for Caterpillar ELC.
_ Pink is Freightliner FleetCharge.
_ Green is Peterbilt factory fill and any aftermarket conventional coolant.
_ Blue is Cummins Fleetguard Compleat
_ Yellow is Ford GO-5
More and more fleets are going with fully-formulated antifreeze coolants to avoid the
necessity of initial charging with supplemental coolant additives (SCA’s). Conventional
and extended life heavy duty coolants showed be monitored by testing (test strips
and/or laboratory analysis) to determine when SCA’s should be added. Be sure the
SCA is the proper one for the type of coolant in use.
Mixing of Coolants
A 10% limit for mixing different coolant types is recommended by engine manufacturers
and ATA’s Technology Maintenance Council (TMC). There is a lot of laboratory test
data that indicates that mixtures of different types of coolants will not provide the
needed protection.
There are three basic types of coolants in common use in the U.S. today –
conventional and two types of extended life. The green conventional is designed to
work at a pH of 8.5 – 10.5. The higher pH helps prevent corrosion and helps to keep
the additives in solution. The extended life coolants can be classified as carboxylate or
hybrid. Carboxylate is another name for OAT coolant and these are designed for a pH
range of 6.0-8.5. The hybrid uses OAT and conventional additives and operates at a
pH of 7.5-8.5.
Many of the new heavy duty antifreeze/coolants use both OAT and conventional
additives, making them hybrids
Mixing more than 10% of the low pH extended life coolants with the high pH
conventional coolants can cause the inorganic additives in the green coolant to come
out of solution and form solid deposits in the cooling system.

[Musicman]

Ummm, my ELC has always been red. Automotive DexCool is orange or yellow. Old ethylene glycol is green. What the heck kinda coolant is brown?

[Lngtaltxn]

Ummm, my ELC has always been red. Automotive DexCool is orange or yellow. Old ethylene glycol is green. What the heck kinda coolant is brown?

rusty water.