Unfortunately I ended up scrapping this car due to rust.I switched my 1994 Tercel to 5w40 Schaeffer after a lifetime of 10w30 WB Rotella and god only knows what the previous owners used. The first OCI noticed an increase in oil consumption but after that it dropped to basically nothing. I was using a quart occasionally in 4500 miles on Rotella and have run 7500 miles on Schaeffer with no make up.
Despite the sludge, or maybe because of it, I still had 170 PSI compression in all cylinders of that engine when it was scrapped.
Consumption was definitely lower with 15w40, I think over almost 2000 miles it used half a quart.