What oil viscosity for 91 tercel?

Answer 1

For driving temperatures: below freezing: 5W30 Freezing-80F: 10W30 80F and greater: 10W40 This is what the original Toyota Tercel owners manual claims. Though it says 10W30 and 10W40 can generally be interchanged on all occasions, but generally use the 10W40 in "warmer" climates. Toyota dealerships now put 5W30 into the car for oil changes. I asked Toyota service about why they use a lighter viscosity for Southern California weather, and they said the lower viscosity was better to protect an older car from engine wear during cold starts and the 30 was just fine for even the warmer months here. Therefore, I think the newer 5W30 oils are fine as a "general" weight. That being said, I have been advised about *never* using full synthetic oil in my older Tercel, since her life has been on organic oils. Sythetics are so good at cleaning that they might allow older cars to develop "new" leaks around aging seals. Semi-synthetics aren't much better than organic oils in sludge avoidance. In an old Tercel, stick with organic oil unless you get *ALL* engine seals replaced.