Take note of this:
http://www.wheels24.co.za/Wheels24/News/General_News/0,,1369-1372-2094_2128428,00.html
To quote:
The Retail Motor Industry Organisation of South Africa (RMI) has issued a warning to South African car owners concerning the grading and quality of anti-freeze available in the local market.
A key component of engine durability in both extremely hot and cold conditions, anti-freeze is commonly available in two configurations, either SANS/SABS 1251 or SANS/SABS 1839.
The key difference between 1251 and 1839 is question of water dilution. Water must be added to dilute 1251 in either a ratio of 50/50 (1:1) or 33,3/67,7 (1:2).
Coolant carrying the 1 839 coding is already diluted with water in a 40/60 ratio and is ready to use. It must not be diluted.
If coolant products carrying the SABS 1 839 mark are too diluted, they become inefficient and corrosion will occur, causing damage to engine components. To eliminate confusion, the RMI has called on the motor industry to recommend the withdrawal of this standard.
A further issue is the presence of completely ineffective coolant products which are hardly anything more than coloured water.
As an experiment, a RMI member bought off the shelf nine samples of anti-freeze RMI Q&S witnessed testing of product for compliance with SANS 1251 or SANS1839. While some conformed to the standard, it was found that others were no more than coloured water, despite the anti-freeze label.
Coolant boiling point is another key factor in it's effectiveness in protecting your car engine.
A characteristic of a good quality coolant is that it will prevent boiling - and these anti-boil characteristics are much more important in most parts in South Africa than the anti-freeze characteristics.
In a good coolant, the content of the vital chemical - mono-ethylene glycol - must not be lower than 30% or higher than 50%. The glycol content can be measured using a hydrometer - an inexpensive piece of equipment that should be available in every workshop.