I wouldn't run 5w20 is anything. Have you heard about the Mazda RX8 problems? Evidently in the US to meet CAFE standards Mazda (In bed w/ Ford) runs 5w20 in their RX8 motors. Everywhere else in the world they supposedly run 5w30. Engine failures are not uncommon in the 5w20 areas especially in the South US where it is HOT. someone at works has a RX8 w/ 20k and already has a new engine Needless to say it will be traded when the warranty runs out.

go with a thicker engine oil. I changed the oil in my g/f's car and it had 5w20 in it, looked like water. I though the 5w30 in one of my cars when really hot was water, but 20w really is water....