Quite honestly, I reckon that a glycol-contaminated sensor is the absolute least of your worries if you have coolant leaks into your oilways. I think I would be more worried about cranks and big-end bearings wearing out due to oil contamination.

If someone is telling your that burnt glycol can destroy a lambda sensor, then they are out to rip you off. They are easily cleaned in ethyl alcohol. The lambda sensor is the sensor that determines the amount of uncombined oxygen (or ozone) in the exhaust strem, and it acts as the exhaust "sniffer" that closes the loop in the feedback system controlled by the ECU. It is not the only sensor, however; if it fails, it is likely your engine will just run rich. Second hand ones from scrappers are a lot cheaper than new ones; having said that, I've never had one fail on me in any car I've had, and my mate (owner of Liverpool's main Bosch diagnostic centre) reckons that they are the last things to go, since they are usually ceramic and palladium.

Likewise for cats - they aren't likely to be screwed by a bit of boiled coolant, no matter how much fuel or oil is in there with it. The coolant drops their operating temperature so much that they can't cook - so all they do is fail to operate, not fail completely.

If you've burst a head gasket you should not try to continue to drive with it, as you will pressurise your cooling system (burst radiator and internal heater matrix), push water into the oil (knackered crank, big ends, small ends, cam shaft bearings, oil pump) warp the cylinder head (damaging the cam bearings, cam, cam sleeves, cam followers), burn the cylinder block face (leading to another failure). The first order of the day is getting the gasket changed and a full engine flush with decent quality hygroscopic oil - assuming the head isn't already warped anyway ...

One of the few remaining Mk1 owners... #00015