MOT Failure on Hydrocarbon and CO2 level

I couldnt tell you why oil temp doesnt follow water temp, but I can tell you that if it takes 5 mins and say 2 miles to reach full water temp, it takes almost double that for an oil temp of ~80deg C, longer if its a diesel.

Tim..

..because it's the water that sits in the water jacket around the combustion chamber not the oil. Some cars these days have "dummy" temp gauges which only show cold, normal and too hot and won't show inbetween so they can't always be relied upon.

Bloody well hope not.

This is an acceptable explanation. Andrew Morton's explanation is in the same vane.

The central issue is whether the chambers are hot enough in time for the combustion of the air-fuel mixture in the optimal ratio. The recognition of the tardy warming up of the engine lubricant is a distraction. The rapid rise of temperature in the metal (specific heat of metal is 4 times that of water) causes at ignition a correspondingly rapid rise in the coolant at first. When oil starts coating the chambers in quantity, this rise (of all three elements, from inside out: oil, metal, and water) is somewhat slowed down. So, I contend that as soon as the coolant temperature light goes out, the metal (i.e. the space within which the all important -- in determining the proportion and composition of the gaseous end products -- chemical 'burning' is taking place) which *leads* the way in the rise of the temperatures should be hot enough. The oil temperature may still lag behind at this stage; it does not accurately reflects the actual temperature of the chambers but is ultimately less important than the coolant temperature in telling us if the condition of the chambers is ripe for an optimal combustion.

Sorry, as soon as the coolant blue light comes on. (And, it does not accurately reflect. Not "reflects". Duh)

Duncan Wood ( snipped-for-privacy@dmx512.co.uk) gurgled happily, sounding much like they were saying :

Few cars have two lambdas - I certainly don't think a 1.1 Paxo does.