After testing 30+ oil brands and grades, I determined that Pennzoil Conventional 10w30 and Pennzoil Ultra Platium 10w30 provided the smoothest and quietest operation in my Subaru but the Delo 15w30 I have in it now is impressive. The engine is more smooth and quiet at hot idle than ever before after 2300 miles. Delo 15w30 runs much better than the Rotella T5 10w30 I ran previously. It should keep the engine much cleaner as well.
http://thisissevereduty.com/product
Now I am Done
http://thisissevereduty.com/product
Now I am Done