I have a 1.6, 2001 petrol Focus, with 80,000 miles. It has excessive oil consumption, no leaks, must be burning it. Emissions only just passed last MOT. No smoke seen though. It recently broke down, due to lack of power (didn’t do hills, 25mph up M11...not good) – this was discovered to be due to catalytic converter being clogged up, so exhaust gases couldn’t escape. Probably due to burning oil residue. Got that fixed, now need to sort cause of burning. I stupidly managed to leave the oil cap off after re-filling a few months back. I only noticed (at the end of a long trip) as it was making a funny whining noise when I depress the clutch (whining whirry noise, fairly low pitched, not a squeak or squeal). Might not be related, but started then, and don’t believe in coincidences! Other interesting evidence is from no3 spark plug (see attachment for photo). New ones were put in ~ March, on recent checking, three were fine (if oily), but one had a horrible cancer on it, pale grey/brown, off white lumpy stuff, a bit like lime scale. Haynes says likely to be valve guides. Friend thinks more likely to be rings, as if (just) valves then should see smoke in exhaust when free wheeling/engine breaking. Any thoughts/opinions/advice much appreciated! Particularly how can I test which it is, without spending another fortune? Thanks!