Bought my '91 with 85k miles from an old lady who took it to Wal-Mart for service.
It was 2 quarts low when I bought it and the oil was chunky and f'n nasy. Somehow thinking I'd be getting an SR in a few months anyway, I bought it. I've since put 23k more miles on it. Ran 5W-30 Mobil1 the first change and it just gobbled up oil. I think I burned a quart every 1000. Put in 15w-50 Mobil1 and now it burns about a quart every 1500. Haven't bothered trying dino juice since I'd happily burn a little oil just and know that at least my main bearings will be happy. I just used some ring and piston cleaner, the kind where you pour 4 oz. in each cylinder, let it sit for 2 hours, then crank it with plugs out to blow all the crap out. Very nasty. The car left an Uncle Buck style cloud around town as it burned all the **** out! Results pending, but so far so good.