Nor me. Halfords own site says take oil to an oil recycling centre, not bring it back: http://www.halfords....s&pc=categories
And simple arithmetic says that antifreeze diluted to 25% won't go back in the container you bought the new stuff in.
And, grabbing a research topic, I hate to let it go unresolved.
This report was prepared by Dr Stuart Dobson, of the UK's Institute of Terrestrial Ecology, for the UN's International Programme on Chemical Safety (IPCS), in 2000.
It's quite long but there is an "Executive Summary", which i will pull the bones out of.
Ethylene glycol released to the atmosphere will be degraded by reaction with hydroxyl radicals; the half-life for the compound in this reaction has been estimated at between 0.3 and 3.5 days.
Ethylene glycol is readily biodegradable in standard tests using sewage sludge. Many studies show biodegradation under both aerobic and anaerobic conditions.
Ethylene glycol has generally low toxicity to aquatic organisms. Toxic thresholds for microorganisms are above 1000 mg/litre.
Terrestrial organisms are much less likely to be exposed to ethylene glycol and generally show low sensitivity to the compound.
Dr.Dobson makes no recomendation about disposal. He reports that the UK used 12500 TONNES of glycol antifreeze a year, but seemed most concerned for wildlife around concentrated-use areas such as airports that used it to de-ice aircraft. My interpretation is that domestic disposal down the loo is acceptable.
Edited by john.r.davies, 10 May 2018 - 08:57 AM.