How does a modern 5w30 compare to a 1990s 10w30

My GS350 burned a quart in 300 miles on the highway at one point. It took two Valvoline Restore and Protect changes of 5K each to take it back to not burning at all. I didn't feel any change in power generation.
It wasn't 1 quart in 1000 miles?

 
It wasn't 1 quart in 1000 miles?

My worst case was 300 on a roadtrip which prompted me to start trying to fix it. Driving around town was closer to 600 miles a quart. I tried a bunch of various additives like MMO, BGR etc and it kind of hovered around 1K when Valvoline Restore and Protect went in.

Edit: I just noticed you linked my original post. I mentioned the 300 mile trip there. I had to make an emergency pitstop at a walmart to pick up some 5W30. :)
 
My worst case was 300 on a roadtrip which prompted me to start trying to fix it. Driving around town was closer to 600 miles a quart. I tried a bunch of various additives like MMO, BGR etc and it kind of hovered around 1K when Valvoline Restore and Protect went in.
Mhm.

It's quite the miracle sauce.
 
Even if the oil control ring was packed solid, you still wouldn't be consuming this much oil. When we tore down my buddy's high mileage (>200,000 miles) HO, that had like no oil pressure (~12psi on 20W-50), we found all the oil control rings were plugged solid. It didn't consume anywhere near as much oil as you are.

Another HO we tore down (bought the car with the engine known bad) was like yours: #8 was a disaster, fouling plugs, drinking oil, it had some rather major scoring in the bore, which, IIRC, was due to a broken ring, though I may be misremembering, it's been a while. And yes, it still ran strong, just like yours does, which is why I suspect that there's damage to that hole unfortunately.
If there is a scored cylinder, so be it. We'll run it while we can and there is a good chance it will survive until the rebuild anyway, since it gets driven about 1000-1250 miles per year, which is why Valvoline Restore and Protect is not going to do so much as it takes 4 years to do a normal 5K on the oil. We'll have to get a bore scope and look down there to see if there is any scoring. You would think if the scoring is actively worsening, the consumption would increase but it is not--yet anyway.
 
Even if the oil control ring was packed solid, you still wouldn't be consuming this much oil. When we tore down my buddy's high mileage (>200,000 miles) HO, that had like no oil pressure (~12psi on 20W-50), we found all the oil control rings were plugged solid. It didn't consume anywhere near as much oil as you are.

Another HO we tore down (bought the car with the engine known bad) was like yours: #8 was a disaster, fouling plugs, drinking oil, it had some rather major scoring in the bore, which, IIRC, was due to a broken ring, though I may be misremembering, it's been a while. And yes, it still ran strong, just like yours does, which is why I suspect that there's damage to that hole unfortunately.
I found pictures!
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If there is a scored cylinder, so be it. We'll run it while we can and there is a good chance it will survive until the rebuild anyway, since it gets driven about 1000-1250 miles per year, which is why Valvoline Restore and Protect is not going to do so much as it takes 4 years to do a normal 5K on the oil. We'll have to get a bore scope and look down there to see if there is any scoring. You would think if the scoring is actively worsening, the consumption would increase but it is not--yet anyway.
FWIW, what I've done is simply buy a stock longblock or shortblock, though in your case, since it's not modded, a longblock probably makes the most sense. Take a weekend, swap it out, don't have to fart around with a rebuild. The stock parts are very good, particularly the earlier engines with the forged internals (which you don't have, being a '92, it will have the hypereutectic slugs). Just keep an eye out for a low mileage one and snap it up.
 
FWIW, what I've done is simply buy a stock longblock or shortblock, though in your case, since it's not modded, a longblock probably makes the most sense. Take a weekend, swap it out, don't have to fart around with a rebuild. The stock parts are very good, particularly the earlier engines with the forged internals (which you don't have, being a '92, it will have the hypereutectic slugs). Just keep an eye out for a low mileage one and snap it up.
Don't waste your time. He clearly wants to just dump random chemicals in it and flex that money is no object. Complete waste of a thread.
 
One quart per 300 miles? I can top that. My former 2001 Volvo V70XC blew a seal in the mountains of West Virginia running hot and loaded to the gunnels. It went through four quarts in under fifty miles before I realized that there was a problem. After topping it up it went through another three quarts in thirty miles. Not that it matters, but this was Mobil 1 0w-40.
 
I have no idea how that would go. The Coyote is a totally different engine and probably takes a 5w20. But I am old school and love those old pushrod engines.

I'll just add that in spite of the huge oil consumption, the car runs like a champ. It's got 156,000 miles on it. I had some trouble with the left rear plug fouling, but put in a non-fouler with an E3 Plug and the car runs great (1300 miles and still not fouled). This year, after an engine flush with the Amsoil product, it is running better than ever. Back in 2023 I would get oil smoke wafting past me at a stop light on a breezy day. Now I hardly notice the smoke.
Have you considered rebuilding the engine?
 
The PCV screen I took out in Oct 2023.
No idea how long the old screen was in the car. The seller did not have maintenance records.

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Just pulled the new screen out and what a bear getting at it down the back of the engine nearly jammed against the firewall. Here is the new screen after 2815 miles (and about 10 quarts out the tailpipe):
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There is a huge difference between the SL oil recommended in 1992 to oils of today.

Um, SL? More like SF I think without checking....

Later it was SH, and then SJ came out in the late 90's featuring the initial gen of standardized hydrocracked base oils....
 
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