We would recommend the Halfords Advanced antifreeze which is recommended for aluminium engines. Always flush the cooling system before adding new antifreeze. Our Halfords advanced antifreeze is MEG based and is organic acid technology.

For a 1994-2005 1.8 MX5 the capacity is 6litres and a min of 35% coolant is recommended (max 65%)

Peugeot's of this era were fitted with an organic acid technology (OAT) coolant. If this is still fitted then you would be better to use Halfords Advanced Antifreeze. A 50:50 mix would be fine.

Halfords Advanced Antifreeze rather than Halfords Antifreeze would be the product to use for a 2001 SAAB.

All the antifreeze and coolants sold under the Halfords brand are ethylene glycol based so this product should be suitable for your application.

Subaru have been fitting Organic Acid Techology (OAT) coolants for some years now. Halfords Advanced Antifreeze is such a fluid and you should use this (and not the standard product) for your application. The product code for the Halfords Advanced Antifreeze in 1 litre pack is 798769.

Vauxhall's of this age fitted an Organic Acid Technology (OAT) coolant as standard. Halfords Advanced Antifreeze is such a product and would be the best option.

BMW recommend a hybrid antifreeze which is not quite the same as this Halfords grade. You probably won't have any problems using this but if you want the actual OEM approved product then you want one based on BASF Glysantin G48. These are available in the UK and are generally green in colour.

VW started using Organic Acid Technology (OAT) coolants from about 1996 so all Mk 4 Golf's would have been filled with this type of product. Halford's Advanced Antifreeze is an OAT product so assuming that your vehicle still contains the type of coolant that was first fitted that would be the product you want rather than this one.

I guess that although the engine is not overheating it is possible that there could be some incipient boiling somewhere in the system and this is being heard from the expansion tank. In this case increasing the concentration of antifreeze in the water could prevent it. Don't go above 60% antifreeze though as you will start to get lower freeze protection and might see problems with the viscosity of the coolant getting too high. Also most Mitsubishi cars would be better suited with a product such as Halfords Advanced Antifreeze rather than this product.