I started using 'Marvel Mystery Oil' as an additive, oil & gas.
I added 'MMO' about 500 miles before the next oil change.
I suggest that you add Marvel Mystery Oil to both the crankcase and your fuel tank. When you change your oil, replace either a pint or a quart of the 10W40 oil with Marvel Mystery Oil. Do this at each oil change. When you add oil between oil changes, use the Quaker 10W40.
In the gas tank, add 4 ounces of Marvel Mystery Oil for every 10 gallons of gasoline. Once again, do this at each fill-up.
On the Honda, I've noticed a great difference in acceleration as well as color of my oil.
Before the oil always looked golden brown, but since adding the MMO, the oil is black which means it is actually breaking loose the grim and varnish caused by heat and lack of oil change.
Make sure you get a good oil filter because after adding the MMO, it will fill up your oil filter with all the grim it has broken up.
I popped off the Valve cover on my engine and was amazed at how clean the valve/valve springs were, because before they were dark brown and had a vanish look due to the heat and old oil. Now they look as if I had dumped them into a solvent bath. Trust me this is a good thing!
The idle is now normal and you can not even feel the vibration like before, smooth I tell you.