I have a 1989 Toyota Camry. It has 203,900 miles on it right now. I have used Mobil1 in it for a long time now. I have switched it to Castrol 10-30. It burns off a lot of oil. I have also tried 10-40, and 5-30. No difference. What if I tried 5-20? Would the thinner oil get through my cylinder walls easier? My mechanic says that the oil is getting forced throught the walls in the old age. If I were to put 5-20 in, could I use the Motorcraft oil? Even though it says it's meant for Ford and Mercury?
Thanks!