20XE burning oil

My "1000 miles of trouble free motoring" celebration is a little premature I think.

Went out for a blast yesterday and did probably 150 miles, and it looks like in this time it used just under 0.5L of oil. Can't see any leaks so initial assumption is it's burning it.

Engine was rebuilt by me 1000 miles ago with new pistons, rings, Cometic headgasket, new stem seals etc.

A few mates followed me out the weekend before last and said it smoked a bit on overrun but not under acceleration so assume this is when it's burning it.

Suggestions? Planning on doing a compression test and checking the plugs while they're out...

When its left overnight and you first start it up do you get a bit of blue smoke at first start up?

Sounds like the stem seals.
Which is a head off job :(

I tried starting it/revving it from cold today and there was no blue smoke, nothing noticeable anyway

A newly built engine will use a bit of oil and if you are driving it hard it will use a bit of oil too, I would monitor the issue and see if the consumption gets worse. What oil are you running it on?

10/40 mineral oil. Expected some oil loss up to 500 odd miles but had expected it to stop using as much by now?

Oh forgot to say, removed the plugs and #3 looked a bit black and shiny on the threads, but the tips overall looked okay.

If its used .5 litres that quickly you should notice if its burning it (smoke etc)

But as said - it will burn a bit more than normal as its a fresh lump, so I wouldnt worry.

I'll get it up in the air and double check for leaks then, I don't see plumes of blue smoke in the rear view mirror! I'll give it another 1000 miles before worrying then :)

I take it you've run it in correctly ?

Had it under load and engine braking almost constantly without going over 4000rpm for the first 500 miles, oil changes at 100 and 500 miles with mineral oil.

Had someone follow me today down the lanes, it produces a little bit of blue smoke on powering on and a bit more when letting off. Not producing enough for me to see in the rear view though.

It also smells really bad if you're behind it.

Got through another 0.5L or so in the past few days again...

Suggestions?

Edit: its now done 1500 miles btw