< 10W30 is strictly a GASOLINE Oil.
<
well..... that isn't really accurate.
10w30 is 10 weight oil with similiar behavior to 30 weight when heated.
its still a 10 weight oil when heated according to my viscosity cup though so...
the specification you need to look at is the "service rating" such as cd,cg,sd, et cetera. use the service rating called for in the owners manual when using non original equipment oils. the rating includes within it breakdown temps, mechanical pressure rating of the oil film, detergent specifications, and some other more esoteric information that sounds rather gobblegookish if you don't speak tech on a regular basis.

as an aside, not all high mileage motors will benefit from a thicker oil. eg honda and mazda spark ignition motors frequently call for 5w30 and using a 10w30 will cause valvetrain failure due to lack of lubrication. yep been there done that dangit. (racing is a different world since we usually rebuild those motors every season, sometimes more often) also expect a decrease in fuel economy with thicker oil, after all its more work for the motor to do pumping that stuff and that means in my experience the driver tends to develop a longer right leg to overcome the loss in available power at a given throttle setting.