Thought it was too good to be true, car lasted a whole three weeks since last repair.

any ideas what can cause this:

1. Dipstick Blown Out
2. Grey smoke when backing off full throttle (only at 100mph +)
3. Smoke on start up
4. Plug on cylinder 1 found with oil foul

Done a compression check and found all cylinders to be at 150psi so don't think it can be piston or rings as i first feared.

Could it be valve stem oil seals?