Time for a rebuild? :/
 

I’ve been trying to fix an issue I have with my GSL-SE that includes lowered oil pressure at high rpm and lots of bluish-gray smoke from the exhaust. I’m well aware that I’m burning way too much oil (like a quart every 400-500 miles) but what worries me is that it’s only happening under stress. I’ve tried using thicker oils but that hasn’t worked.

I’ve read posts that say when this occurs the oil seals have worn and can only be remedied by a rebuild. Is it the only option for me?

How many miles? Original engine? Any mods?

From your quick description, the only thing you're missing is hard starting and won't restart when hot. When you hit those symptoms, you don't have much time left.

Original 13B, no direct engine mods, just several smog deletes.
Miles are a bit strange - for the record I'm not the greatest car purchaser :facepalm:... I was told the engine was rebuilt 20k miles before I bought it. If that's true I probably have 25-26k.
If it isn't (which I have a sneaking suspicion could be true), then it could be... anything. I doubt its the 274k the car theoretically has. I'm sure its been rebuilt but I'm not sure if they told me the exact truth.
The engine doesn't seem to act that high mileage to me, idk. Starts great, just need to give it some gas when it's cold and it doesn't have trouble starting when warm.

Tell us more about "...lots of blue smoke" and "...under stress".

Without knowing the rebuild history of the engine (*parts lists, receipts, write-up, etc.), anything is a guess. If the odometer shows 274k miles,,and you've put 25k miles on it since you've owned it, and you were told it was rebuilt 20-25k miles before you bought it, that puts the rebuild mileage at about ~225k miles, which sounds about right for a 3mm Apex Seal 13b that was well cared-for. My own original 13b SE engine went 221k, and I know it's entire history, as my dad bought it new.

So, the mileage adds up to what you've stated, and another 50k miles since rebuild gets you to now. I wouldn't expect a SE rebuild to go only 50k miles, so have to assume that some parts were reused during the rebuild. If some of those parts were the Oil Control Rings, that could explain high oil burn rate and the smoke. As the engine RPM increases, the vacuum on the intake side goes way up, which can suck oil past the Oil Control Rings into the intake charge, where that oil then gets burned during combustion.

The good news is that the Apex and Side Seals seem fine, or it would lose compression along with vacuum - loss of compression is a sure sign of imminent hard seal failure, and leads to hard starting and inability to start when hot. In this case, you could run it like this for quite some time as long as you don't mind the smoke and keep up on the oil level to ensure it never runs low. Letting the oil run out, starving the engine, will instantly overheat and ruin the engine. Treat it gently, and you might put off a rebuild for another 10k-15k miles, but no guarantees...

Ok, that's what my friend recommended to me: run the engine til it starts to have real issues. That's what I think I'll do then.
Thanks for the insight!

Well, that's one option.

Keep in mind that 13b cores are more available than 12a housings, but SE 13b has the coolant seals in a different place than later 86+ engines. Hence, finding a replacement engine doing mix-and-match has it's problems. Running your engine until you experience 'serious problems' could mean that your hard seals (Apex, Corner, Side seals) have chewed through the chrome on your housings, making them unsuitable for rebuild. At that point, you'll be looking for a replacement S3 engine, core in usable condition, or expensive new housings...

NOT waiting until you have serious problems evident could save a lot of $$$, time, and hassle if you just saved and planned for a rebuild in your near future. Something to think about, and depends on how much you love the car and how long you intend to keep it. My original engine sits on a stand in the corner of my garage, awaiting rebuild so I have a known good core ready when the one I'm running now shows signs of weakness...