I just had my 2008 SC430 with 37k miles have the 45k service done at JM Lexus. They used 0w-20 and next service is set for 52k miles.

http://lexus2.custhelp.com/app/answe...ynthetic-oil%3

http://carspecmn.com/toyota-and-lexu...ynthetic-0w20/

 

I'd run either M1 High Mileage or Pennzoil High Mileage in 5w-30 full synthetic. They can typically be purchased at Walmart depending on seasonal sales for about $22-27 per 5 quart jug. Just buy what ever is on sale when you need oil. You can stay with one brand or alternate using oil brands with no ill effect.

http://www.pennzoil.com/en_us/produc...h-mileage.html

https://mobiloil.com/en/motor-oils/m...1-high-mileage