i have a 1988 rx7 non-turbo and i was wondering what kind of oil would be best for the upcoming spring and summer months. i will just be in southern ontario so the conditions won't be extreme and it will just be for casual everyday use as well as some highway driving. I'd appreciate your input. i'm changing the oil today. thanks!

 

Castrol 10w30.

 

Well you should have searched for this first... there are probably 20 threads asking the same question.

But according to Mazda:

average temps above 20F: 20W50
average temps below 30F: 10W30
average temps below 0F: 5W30

BTW: this info is also found under the hood on a factory hood sticker, in the factory owners manual and shop manuals.

So what will the temp be in your area?

Personally I recommend you avoid 10W40 or 10W50 (too many additives to get that range, which leads to a higher ash content), and once you pick an oil (like Castrol) stick with only that brand in a car...