is it bad 2 mix coolant???

[SS 1998]

i was doing the general checks on the car the other day. and realised i needed a top up of coolant.
and someone told me not to put coolant in it bcoz it will crystallize with the coolant thats in it now.
is this true???
cheers ct/ss1998

[VT_Cruiser]

From what i have been told in the past, its fine as long as the chemical base of the old coolant is the same as the new stuff, and we assume the existing coolant is the correct type for your engine. There were 2 different chemical bases then. Ethylene Glycol for cast blocks and heads which is fairly acidic, and Propylene Glycol which is less acidic and used with alloy heads and blocks. Not a good i dea to mix the two as the chemical bases are different, and not a good idea to use the ethylene glycol in an alloy motor as it will do damage over time. I have always just drained the existing and put in the recommended specified coolant type, its cheap and gives me piece of mind. This info as about 5 years old tho when i enquired, others may know alot more.

[accentstencil]

Unless you know what type of coolant is in it already then it is not a good idea to add more coolant which will possibly be different. As VT Cruiser said, drain the coolant and replace with coolant that meets the specifications for your engine, that way you know what's in there and you can top up with the same type.

[SS 1998]

sweet as guys......thanks heaps 4 that.

[Road Runner]

Hi,
All the feedback sounds good to me, the only point I'd like to mention is when unsure of the coolant type or brand you can just top up with distilled water.
I have done this many times in the past with both mine and others cars and was recommended to do this where i get my block and radiator flushed each year.
Cheers
RR

[edals]

Dont mix ya Coolants, It can react between the 2 and you can end up blowing hoses, just flush the whole system and replace it.

[jeffyvt]

im a mechanic and i kno 4 sure that u sould never mix coolant they r a diffrent chemical and they will corode and cause problems