I used to run a mid grade,(Canadian Tire brand oil)for years, and it developed a tick almost like an old Chrysler, our local engine rebuilder stated to lose that oil and replace it with Castrol gtx 10w30 and add 1 bottle of Lucas oil stabilizer,he said it's a good product.I did and the tick went away,immediately. I don't use Lucas anymore but Ithink that it helped...Shell Rotella T 10w30 will be my next oil unless you recommend otherwise.