(Sorry this turned out quite long, but I hope it gives a fuller picture)
I've recently bought an Astra automatic Envoy 1.6 8V 2001. The garage said they did an oil, air filter, and spark plug change.
On rare, very rare, occaissions it would stall at junctions. Intermittantly the service(?) light (car with a spanner symbol) would come on and the mileage display would say "inspect" on it. Did a 300 mile round trip via East Anglia and all seemed fine, apart from stalling in a shopping centre car park, uphill spiral with a full passenger load (I had to change from D to 1 on the automatic transmission). Engine oil seemd low so topped up with cheap oil (to 3 out of 4 squares on the dipstick). After coming back home, I check the oil and it's almost gone. No signs of leak but possible seepage as certain parts of the engine are greasy? Is it just cheap oil?
Took it back to the garage and they "fixed" the error/service lights. They gave a printout with 3 error codes with "not present" underneath each code. I'll provide the exact details later. All seemed well...
One day, start the car and it rattles and thuds briefly as it starts. I was running errands that day, each time I started the car the rattle/thud got more severe. I'm like WTF has the oil ran out? Check the oil it is fine, then see the coolant reservoir is EMPTY. Should have checked the dash for any messages/engine temp before filling with water. Immediate results as the car starts smoothly. Next day I see water dripping from the side of the radiator Head to Halfords and buy coolant and Radweld crack repair. Seemed to have fixed it, no leak and coolant level is stable in reservoir. Although I have a feeling there is a slight leak there...
Took the car back to the garage to sort out a wiper motor and a loose heatshield round the exhaust. As I'm leaving, the car vibrates on idle, I open the bonnet and see the engine shaking more and more WTF OMG is my engine about to break apart?! ... And then it stalled. The teapot (ECU?) light came on the dash. The garage guys looked at the engine and checked the spark plugs and cylinders, they replaced spark plug 1 with one off another car. The old spark plug taken out of mine had some oil on it apparently. Computer check says Cylinder 3 also needs checking. They recommended I change all the spark plugs, which they'll fit for free... With one sparkplug changed I head home. All seems fine, did about 30 miles over the weekend (planning to change the spark plugs Monday/Tuesday, as soon as I get the chance). Had to move the car for parking this morning and it was vibrating the same, misfiring on idle, but as I sped up it reduced.
When I bought the car just over a month ago, didn't they put in new spark plugs? Maybe they put in used ones?
I've got a feeling there's a more serious underlying problem with the car?
Any comments and advice on this greatly appreciated.