Hey guys,

I've got an '87 Sammy with 90k miles on it.

I'm getting smoke from the exhaust pretty regularly. It's most noticeable/prevalent when downshifting and decelerating. This could be just because the smoke is catching up with me, but I think that it's also because the engine is revving up and the back-pressure through the exhaust system is changing.

This is also more when the engine is cold/beginning of the day.
I don't see an oil leak (nothing on the garage floor)
But I am burning a bit of oil as well and need to top off every month or so.

What I've heard is that it's probably the valve seals needing replacement and so there's a bit of oil getting in overnight, then burning through the exhaust.

Does that make sense?  Any other ideas?  Is there an easy way to check the valve stems? 

Any help is much appreciated.   

Ya could be valve stem seals and it could also be rings. At 90k, I would have the whole head gone through by a machine shop. But thats just me.

Depending on how its been treated, 90k miles is not too soon to be looking at a rebuild.
A "bit" of oil, is a vague amount.  Some people have different opinions, on what equals a "bit".
Have you done a compression test?  That would be the first place to start.
You usually see the oil burning more easily on a cold engine, as a warm engine will burn quite a "bit" of oil, without it being real obvious.
There is no easy way to test valve stem seals and they are a pain to change, while the head is on the engine.
I replaced the valve stem seals, on a 1.3 that was using about a quart every 500.  They were hard, brittle and broke apart, when removed.  It was smoking on deceleration and between shifts only.  The consumption went down to a quart every 800.  Not much of an improvement, or, worth the effort.
The motor is still running fine, but no longer in my daily driver.

is it just me or do the 1.3's almost always burn?

If you ask it that way - I'd have to answer - just you.

I have a 1.3 on which the oil consumption is negligible - and by negligible I mean I cannot detect any drop in level between changes - now that it has been rebuilt.

The 1.3 is like any other piston engine, if the rings/bores are worn they will burn oil, if the valve seals are worn they will burn oil, you either live with it & top up as necessary, or when it reaches a point where you consider the consumption excessive, you rebuild or get rid of it, replacing it with a used engine, just gets you back to the "live with it" decision point.

I had my car from new, at which point it used no oil between changes, the oil consumption increased with time & distance covered, until I rebuilt it, which took it back to the no oil between changes state - almost five years and forty thousand miles post rebuild, the consumption is still negligible.

X2  on having compression test done....... establishes a baseline on condition of engine. On my 92 efi 1.3, burned quart every 300 miles, still ran ok till exhaust clogged up and fell apart. I was fumagating the neighborhood till engine finally died. 3 weeks and $2000.00 later I'm back on road,  new engine and exhaust. Night and day

 I'd say the culprit is in the top end of the motor. Guides .....
If it were rings it would smoke all the time.
 The problem is: if one rebuilds just the top end of an engine , ignoring the bottom, disaster may ensue.
I'd be looking into a minor rebuild at the very least ) if I were you. IE : guides , valve grind and rings....

I'd say the culprit is in the top end of the motor. Guides .....
If it were rings it would smoke all the time.

From personal experience with a G13B, I cannot agree with this...

120,000 miles, no leaks, burning a fair bit of oil and the only time you saw smoke from the exhaust was on an upshift, and even then, you had to be in a car following, and watching for it, because all you got was the merest puff - dry compression was way down, around 115/120 psi, wet compression was around 199, piston~wall clearance was actually within spec. (just barely), and the pistons still had the factory knurling visible.

  Not looking for agreement here....Just trying to help out.....
Been doing this for a while.....