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Does anyone know how reliable is this Clarke CHT433 Anti-Freeze & Coolant Tester that Machine Mart (machinemart.co.uk) sells for £ 3.51?

I drained the radiator and fill in then 3 litres of Castrol Antifreeze, 2 litres of water and 1.5 litres must have remained in the system as the Haynes manual says 6.5 litres with external expansion tank.

So the concentration of antifreeze should be at least 46% (3 l antifreeze of 6.5 l in total), but the tester says repeatedly less than -12°C.

What's this?


Car was driving about 3 miles before testing the coolant.

Two other cars show a concentration for -18°C resp. -22°C with this tester, but I haven't filled up the system and don't know the real concentration in there.

i had a cheapie tester....is yours the one with floating balls?? mine was rubbish

i wouldnt stress, 3ltr of antifreeze is plenty enough for sure

My one has a rubber ball to suck the liquid and a red plastic arrow to point to the scale.

Yours is a very fragile tube out of glas with a ball inside? Mine is all plastic.

Well, if yours were rubbish and mine's is the same price, too, ...

Maybe I'll ask the nearby Volkswagen dealer. After 22 years, the car has presumably no warranty anymore, but may they check this just for a laugh as I buy some parts there from time to time.

i wouldnt even worry mate.....3ltrs is plenty enough it will never freeze up

as a guide...at the vauxhall dealer i worked at , they put in 2ltrs in most cars bigger than yours and it passes their tester

just have your best guess at it mate, then put an extra 250ml of neat antifreeze in or thereabouts.

unless we have an absolutely spectacular winter then you shouldn't have any worries. i think i was probably running a far worse mix than that around 2002-2004 and there was a coupla' three nasty cold snaps in those winters... plus my thermostat was rusted open (badly over-cooling). No starting or running problems other than frost crystals blocking any fuel getting out of the feed line one time! certainly it's not gonna freeze up, unless you're in north scotland or whatever - how long d'yer think it's been since we saw more than a couple sustained hours of -12 celcius in britain?