which oil to use?

[philiplang]

I have a 98 boxster and I live in Orange County, CA. Which Mobile One oil should I use? I got mix info from different people. Thanks.

[jwgn777]

10W-40 would be just fine. You don't expect ambient temperatures in you region to hit below 30 degrees any time soon. What does you operator manual suggest?

[philiplang]

Thanks for the quick response.
Owner's Manual said10W-40 or higher, in general.
For ambient temp mostly higher than 50F, use 10W-40, 15W-40, or 15W-50. With all this viscosity range, will it make that much different?

[jwgn777]

You won't see much difference. You will get better fuel economy and faster cold engine starts with a 5-40 as opposed to a 15-50. Most people won't even notice that either. 15-50 is gear toward high temperature operation with high ambient out side temperatures and is good for server duty operation like racing a turbo vehicle or towing. You can basically use all these oils in your climate. Zinc base oils provide the best protection however they are being taken off the market due to the fact that they contaminate and destroy catalytic converters. Also multi grade oils have lot of additives in them as opposed to straight 30w these additive is what makes the oil multi grade. this increases the chances of thermal beak down if you leave the oil in you vehicle for a long time. Just make sure you chance you oil regularly.