Rattle and knock on 87 octane - 1999 v6 3.4

Does anyone else with the 3.4L v6 have trouble running 87 octane gas?

I bought mine new in 1999 and to this day it runs fantastic, but for as long as I can remember when I use 87 octane gas it's a crap shoot as to whether it's going knock and rattle or run OK for that tank of fuel. I've tried different brands of gas and there's no consistency. When I get a tank of 87 that rattles, if I add 4 or 5 gallons of 89 or 91 then the problem is instantly cured. In the past I just ran 89, but prices have changed and now in my area 89 is $.50/gal more than 87, so if this problem is unique to my truck then I would really like to figure out why and get it fixed.

 

Sounds like you should just run 89. Getting the the root of your issue will likely cost more than an additional $.50/gal.

A cheap potential fix would be colder spark plugs.

 

Might just be the additives in your gas down there.

I run 87 all the time with no problems

I have bought gas all over the Northeast

 

It is known that some of the 5vz are just really ping happy. Maybe a mfg defect. Maybe some carbon buildup. How do your spark plugs look? I'd personally just run 89 and deal with it. I run 93 ethanol free in mine all the time.