Exactly. I fail to see what could be possibly wrong with any A1/B1 in most of the Japanese vehicles (when it was current), or a current A5/B5, despite it not being a 20, or any 0w-20 or 5w-20, where a 20 is specified, assuming sensible OCIs.
Even General Motors has gotten rid of AC Delco 5w-20 dexos1 in favour of AC Delco 0w-20 dexos1, stating that the 0w-20 is suitable wherever 5w-20 had been previously specified.
With the comments above to not use 10w30 in a GM vehicle requiring 5w30, at least up until that point, GM was making a lot of sense. You ask GM today what motor oil to use in a 30 year old gasser, or a 40 year old gasser, they'll tell you a dexos1 5w30. Before that, it was the 5w30 of whatever numbered spec was appropriate. It has been pretty simple, and I wish GM had stuck with having dexos1 being viscosity dependent as a 0w30 or 5w30 ILSAC type. It's not that 10w30 can't work in a modern 5w30 vehicle. GM has a specification that's supposed to simply things for the non-BITOG type customer, at least that's the idea.
Even General Motors has gotten rid of AC Delco 5w-20 dexos1 in favour of AC Delco 0w-20 dexos1, stating that the 0w-20 is suitable wherever 5w-20 had been previously specified.
With the comments above to not use 10w30 in a GM vehicle requiring 5w30, at least up until that point, GM was making a lot of sense. You ask GM today what motor oil to use in a 30 year old gasser, or a 40 year old gasser, they'll tell you a dexos1 5w30. Before that, it was the 5w30 of whatever numbered spec was appropriate. It has been pretty simple, and I wish GM had stuck with having dexos1 being viscosity dependent as a 0w30 or 5w30 ILSAC type. It's not that 10w30 can't work in a modern 5w30 vehicle. GM has a specification that's supposed to simply things for the non-BITOG type customer, at least that's the idea.
