I am the 2nd owner, since 2002, of a 2000 LS with auto.

It now has 165,000 miles and will need its timing belt/water pump done in 20,000 miles.

My concern:
From July til Oct, burned 1/8 qt of oil every 500 miles.

In mid-Oct it burned 1 1/2 qts, in 900 miles.

From Nov til last week, it burned 1/8 qt, every 500 miles.

Mid-Jan, after 900 miles, it burned 1 1/2 qts, again. I replaced the PCV and will continue to monitor, the oil level.

Questions:
When I get the timing belt done, should I have the engine rebuilt?
How long, before the car will start to burn oil, again?
If I have it sleeved, will it last 150,000 miles, before burning oil?

Welcome to the site!

1st off- Have you had a compression test done? That will tell you if your piston rings are bad, and in that case, yes a rebuild is need. You should have between 170-190 lbs on all 4 cylinders- with no more than 10lb difference between all 4. (for example, if 1 cylinder registers 180, the other 3 should be between either 170-180 or 180-190. If you have huge gaps, your rings are shot.) The oil Burning could also be a valve not seated or something like that, so start with a comp. test first.

To answer your second question about how long before it will burn again when rebuilt. If its rebuilt correctly, you shouldnt have any burning issues for 175K+. My LS has 140K+ on it, and the compression is still 180+ on all 4 cylinders. So if you take care of the motor, should last for years and years.

To answer your 3rd question. Sleeving that motor is pointless, unless your going for 400+hp. It just reinforces the block for boost and what not. So if your not gunna boost it, dont worry about sleeving.

Any plans for the car? other than figuring out the burning issue? Clean car btw... rims are alittle big for my taste but eh good platform to start with

I have seen posts, which indicate that you can get a good compression test, yet have a bad oil ring on the piston(s). But, no I haven't tested it.

Is there a way to see if you have some bad valve seals?

Do B18B aluminum block rebuilds, always, use cylinder sleeves?
It's hard to imagine the rings sliding along "bare" aluminum cylinder walls, but ERL (the engine rebuilder) offers both, sleeved and non-sleeved, blocks.

The photos are from last Summer. It has the H/E/I, pullys, and suspension.

doing a leakdown test will tell you the condition that the head is in. Go that route to see if there are bad seals or if a valve isnt seated properly.

like spooner said. do a valve leak down test. and compression test. also resleeving it is pointless if you arent going for high hp. if you were to do a rebuild the most youll have to do is hone the cylinders if there not warped or dont have any deep scratches.

I am contiuning to look, into a stock rebuild.

Regarding the oil leak, I wonder if the worn valve seals and/or worn piston rings will be the only items replaced?

Or will the garage want me to buy valves and pistons?
I've never had any timing or starting issues and I've never had a timing belt break, so I can't believe that I have could bent a valve (in my automatic LS).

i wouldnt think you would need to replace the pistons or valves. id deffinetly make sure the valves arent bent and no bad scores on the sides of the pistons. easy way to tell if you got a bent valve is putting it in a electric drill and and spinning it. all in all you should be fine tho

have u done the compression and leakdown test yet?? If not, start there, easiest way to spot a major problem!