Engineering Bulletin 99-2

	ENGINEERING BULLETIN	99 - 2
July 29, 1999

Coolant System Maintenance
We frequently answer many questions regarding coolant system maintenance. Many questions involve proper system top off, differences between supplemental coolant additives (SCAs), and compatibility between different SCAs. Some information on these topics follows. PROPER COOLANT SYSTEM TOP OFF Properly maintaining a coolant system often involves refilling the system with small amounts of coolant to replace losses due to small leaks, evaporation, or engine maintenance. In order to maintain effective coolant system balance and freeze protection, a 50/50 mixture of antifreeze and water pre-charged with SCA chemicals should be used. Often 100% water or antifreeze is used to top off the system. This may dilute SCA chemical concentrations and can sacrifice system protection. Also, a good quality water such as distilled or deionized should be used when filling or topping off a coolant system. This high quality water helps protect against corrosion and scale build-up. DIFFERENCES BETWEEN SUPPLEMENTAL COOLANT ADDITIVES There are basically two different classes of Supplemental Coolant Additives on the market, Conventional and Organic Acid.		CONVENTIONAL Conventional SCAs are the traditional formulas based on nitrite/borate or nitrite/molybdate inhibitors. These SCA inhibitors are used with coolants commonly colored green, blue, purple, or pink. Baldwin Filters' BTE and BTA PLUS formulas fall into this class of SCAs. ORGANIC ACID Organic acid SCA formulas have more recently been introduced to the US market. These are based on organic acid inhibitors commonly referred to as OAT(Organic Acid Technology) Coolants. They can also be referred to as NOAT(Nitrited Organic Acid Technology) if nitrite has been added to the formula to help protect against liner cavitation. Both of these inhibitor formulas are used in coolants commonly colored orange or orange-red. COMPATIBILITY BETWEEN DIFFERENT SUPPLEMENTAL COOLANT ADDITIVES Because they protect the coolant system through different chemistry, conventional and organic acid SCAs are NOT compatible. Cross contamination by as little as 10% can reduce the effectiveness of both formulas and reduce protection in a coolant system. Below is a chart which summarizes compatibility.

			COMPATIBILITY
SCA	Class	Coolant Color	BTE	BTA +	OAT	NOAT
Nitrite/ Borate (BTE)	Conventional	Green, Blue, Purple, Pink	YES	YES	NO	NO
Nitrite/ Molybdate (BTA PLUS)	Conventional	Green, Blue, Purple, Pink	YES	YES	NO	NO
OAT	Organic Acid	Orange, Orange-red	NO	NO	YES	YES
NOAT	Organic Acid	Orange, Orange-red	NO	NO	YES	YES

If you have any further questions, please
call our Service Engineering Team at
(308) 237-9729

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