Is it OK to use 5W30 oil in a 2000 Buick LeSabre?

yes,5W30 is what you're suppose to be running in it since you have that good COOL air coming off those lakes around MI this time of year.in the summer you can change to 10W30 or run 5W30 all the time.the spec is kind of confusing.it goes like this.1.Use 10W30 in temperatures above 0 degrees.2.Use 5W30 in temperatures below 61 degrees?now does that make sense?when i had one of these several years ago,i ran 5W30 year round.