Old thread, but I recently wondered about 5W-30 vs 5W-20 for my 03 Corolla, since the engine is "backspec'd." Here's what Toyota said when I asked them:
Quote:
Toyota recommends the use of 5W-30 (conventional) oil for installation in your 2003 Corolla. If your local Toyota dealership does not have the required viscosity....
Toyota has transitioned its new vehicles away from using conventional motor oil to using 0W-20 weight synthetic oil. This change is largely the result of higher fuel economy requirements and tightening emissions certification requirements. This does not apply to your 2003 Corolla.
Toyota recommends you use 5W-30 (not 5W-20), as your vehicle is not equally compatible for this oil.
When I asked about whether I should change the oil weight if I switched to synthetic, they said:
Quote:
You can go by the text in the Owner's Manual, which shows the correct grade to use; we do not require that you use a particular brand.
The engine was designed for the recommended oil specifications. Also, your engine will be able to achieve its designed level of efficiency when the correct oil is used.
You can use synthetic oil, but Toyota does not recommend a longer oil change interval using synthetic oil in your vehicle.
If you do use synthetic, Toyota recommends that you follow the same service intervals that Toyota recommends for regular oil use.
It sounds like 5w30 is the way to go, whether synthetic or conventional. Of course, Bob's oil course indicates it can't hurt to go to 0w30 for lower starting viscosity. So I might do that with Synthetic.
Quote:
Toyota recommends the use of 5W-30 (conventional) oil for installation in your 2003 Corolla. If your local Toyota dealership does not have the required viscosity....
Toyota has transitioned its new vehicles away from using conventional motor oil to using 0W-20 weight synthetic oil. This change is largely the result of higher fuel economy requirements and tightening emissions certification requirements. This does not apply to your 2003 Corolla.
Toyota recommends you use 5W-30 (not 5W-20), as your vehicle is not equally compatible for this oil.
When I asked about whether I should change the oil weight if I switched to synthetic, they said:
Quote:
You can go by the text in the Owner's Manual, which shows the correct grade to use; we do not require that you use a particular brand.
The engine was designed for the recommended oil specifications. Also, your engine will be able to achieve its designed level of efficiency when the correct oil is used.
You can use synthetic oil, but Toyota does not recommend a longer oil change interval using synthetic oil in your vehicle.
If you do use synthetic, Toyota recommends that you follow the same service intervals that Toyota recommends for regular oil use.
It sounds like 5w30 is the way to go, whether synthetic or conventional. Of course, Bob's oil course indicates it can't hurt to go to 0w30 for lower starting viscosity. So I might do that with Synthetic.