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  1. #1

    Default Diesel engine questions ~ 6.6 Duramax

    Just got a new truck with the 6.6 duramax. Really like the engine, but is my first diesel. So I have a few questions if you wouldn't mind helping me out...

    - What is the "fast idle" function for in the setup? Why would I use it/not use it?

    - How long should I warm up the truck before I go, if at all? I read before with gas engines you can just drive slowly and let the engine warm up as you drive, is that true for a diesel too? If not, do you always warm it up, even in the summer?

    - I've already found out that it's possible to get a bad batch of fuel. One take I had I got super crappy mileage, next top up my mileage was back to normal. Ever since then I look for the premium diesel, and try to stay away from #2 diesel. The manual says #2 is okay, what's your advice on fuel?

    I probably have more q's but that's all I got for now, thanks.


  2. #2
    Jr. Mechanic
    Join Date
    Mar 2013


    fast idle is the only way a diesel makes heat on startup,at idle they take forever,quicker the heat the more efficient the motor is,with fuel,try to find a fiilup station that has high turnaround,otherthan that a little 911 at a time wont hurt

  3. #3


    Hi Geo, so you would recommend turning on the high idle option?

    And what is 911 fuel?

  4. #4
    Jr. Mechanic
    Join Date
    Mar 2013


    depending on temp.outside.cold out,yes,diesels have cats in the exhaust too,they require heat to function properly,mostly soot,so up to cleans itself,i have old ford diesel with exhaust restricter for cold days,they screw up on occation,the isuzu you have is one heck of a motor,how do you like hitting the throttle hard on that thing?i enjoy it,now 911 is a fuel additive,2 types,hit there site,gain some info.enjoy the power

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