100,000 mile tune up and maintenance questions - Spark plugs, fluids, others ideas...

Discussion in 'Maintenance & Upkeep' started by jmckee6, Aug 13, 2012.

  1. jmckee6

    jmckee6 Rockstar

    I'm just about to hit 100,000 miles in my '99 and am wanting to do some maintenance and replacement of a few parts.
    1) what are the pro's and con's of the expensive spark plugs and wires? Is it worth the $10 each for high end one, or are stock Delco ones just as good?
    2) I keep hearing good and bad things about synthetic differential and transfer case fluids on older vehicles, such as mine. What is your input and thoughts on the topic?
    3) I generally keep pretty up to date with maintenance, so nothing on the truck is broken or at the limit of its lifespan, but what else should one change out at the 100,000 mile marker?

    I am welcome to any input or suggestions. Thank in advance everyone!
  2. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    My 2 cents:

    1. The ACDelco plugs appear to make most GM engines VERY happy.
    2. The synthetics are the way to go.
    3. I like to change the front O2 sensors when I change plugs.

    Have you considered the transmission fluid?
  3. zigger215

    zigger215 Member 2 Years 500 Posts

    I just did this tune up on my 04 5.3 liter. I changed the following

    -all o2 sensors
    -auto light xp iridium plugs (.040 gap)
    -plug wires
    -0-40 mobile one oil change (recommended by a GM wizard)
    -all shocks
    -all rotors and pads all around

    My truck ran great anyways, no issues but it ran AMAZING after these tuneup items were replaced. It got much quieter and my fuel economy did improve!
  4. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I have been told by many GM techs that using the "expensive plugs", ie. xp iridium ect.. Can cause issues with your coil packs over time. They claim that the system was designed for the resistance that the stock delco plugs have and "upgrading" to plugs with a different resistance can burn out the packs. I have not experienced this issue. But, I also always just put the Delco plugs in. I figure if they lasted 100,000 the first time, then why put something different in? I did get talked into a set of the xp iridium by the autozone guy one time. I left them in the truck for about a week. I did not notice any performance difference and out of fear of burning out a coil I replaced them with delco
  5. zigger215

    zigger215 Member 2 Years 500 Posts

    Iridium plug technology is widely misunderstood. Iridium plugs are not designed to give you motor better performance, they are designed with the metal iridium (obviously) which is much much stronger then platinum. Iridium plugs were designed to be a long lasting, durable plug that can with stand the harsh motor environment better then any other type of plug

    A GM tech that says iridium plugs have a differing resistance that the motor was designed for is a MORON! Lol sorry, plugs do not dictate your resistant in the sparking system, your plug wires work with your coils to determine resistance, the plugs are just a catalyst for this outcome.
  6. Skippy

    Skippy Member 2 Years 100 Posts

    Plug resistance most definitely impacts the spark, and the type of metal most definitely impacts the plug resistance. The GM tech is not a moron.

    Copper (more properly, Copper/Nickel alloy) has the least resistance, but also burns away the fastest.
    Platium is about twice as resistant as copper, but the hardness of Platinum makes it far more durable. (80-100K miles are now common)

    Iridium is far more durable than platinum, but also blasted expensive. The resistance of pure iridium is very close to Copper/Nickel alloy, but pure Iridium oxidizes too easily. As a result, the Iridium is used in an alloy without a "standard" across the manufacturers (or even plug lines of the same manufacturer). The result currently is that performance varies, and you may have a design that doesn't work well in your vehicle.

    The smaller post on the iridium plug also is reported to help squelching.

    But here's the thing...

    Regardless of the metal type used, as long as you can create an arc, you create an arc... Over the life of the plug, the greater the gap, the more voltage is required. As long as you can bridge that gap consistently, and the spark ignites the fuel, you're looking at combustion. Iridium seems nice for the longevity, but if you're not getting misfires with platinum, you'll not gain anything with iridium.

    The bottom line is that YES... Resistance is a factor and different metals, manufactured alloys, and plug designs all impact the effectiveness of combustion and durability. There's no such thing as a perfect plug for every application.


    Last edited: Aug 14, 2012
  7. motorking

    motorking New Member

    I am the tech manager at Autolite. XP Iridium plugs for your truck are 6.99 and very comparable to the plugs coming out. AC Delco plugs are all made by Autolite or NGK these days. The plugs that lasted are expensive plugs, copper core plugs will have you changing again in 30k miles. You can learn all about spark plug metalurgy here-
    Using synthetic oils and gear lubes will only make your truck last longer, dont forget about the filters!
  8. 2000sierra

    2000sierra Rockstar

    Curious about o2 sensor's replacement. Could you explain what they do and how they affect the vehicle.
  9. Conlan Rose

    Conlan Rose Epic Member 5+ Years 1000 Posts

    O2 sensors monitor the amount of unburnt fuel by seeing home much oxygen is left in the exhaust. They are vital in modern vehicle to maintain fuel efficiency.
  10. 2000sierra

    2000sierra Rockstar

    Estimated part's cost ? How hard of a replacement is it?

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