Brian,

You're using about 2X the amount of PS prescribed for 'every tank'. 'Normal' use yields 300 gallons trated per 96-oz bottle. My 'marbles in a bucket' GM (Detroit Diesel) 6.5 TD quiets noticeably when I add the PS.

The E300D is not as responsive, but I have read nothing but praise about this product - and it can be found at Walmart near all the motor oils (don't worry, not going there, suffice to say I use only synthetics in my machines)

__________________
BobT
2004.5 Dodge Ram 3500 CTD QC SB 4x4
1999 E300D
Deere 770 w/FEL