You are suggesting adding to diesel, not gas, correct?
I have heard this also. Years ago with one of the 123 diesels I owned, I might have done it. Overall for diesels I swore by Redline additives. Ocassionally I would run a bottle of Techron through with about a half a tank fuel and then change the oil.
I should try the Redline additives for the gas cars. I have only been using Techron, and then changing the oil.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)