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100,000 mile service

1384 Views 7 Replies 5 Participants Last post by  misfit6794
I now have 102,000 miles on 02 DHS. I plan to trade in the car in 50,000 more miles. How important is the spark plug change when the car is running well? Also the tranny fluid information panel still says 100%. Should the fluid be changed anyway? Aside from filters is there anything else that should be done?
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The best way to determine what needs to be changed is to visually inspect it. It is extremely easy to pull a spark plug, once you do, it will be pretty obvious if it has been fouled or not, if they are platinum tipped plugs, they should be fine. Also check you plug wires to see if they are cracked or dried out, more than likely they will be fine. Since the car is running well and you haven't had a drop in mpgs the plugs and wires are probably fine. The transmission fluid should be red or pinkish, if its dark or brownish its time for it to be changed. If you have never changed the fuel filter that would be something to definetly do. Cooling system should be flushed (especially in a northstar) if you have never done it, or its been two years. A very overlooked fluid is the brake fluid, if its original I would have the brakes bled. You can buy test strips at any auto parts store to see how bad it actually is.
You can trust the tranny fluid life monitor but a fluid change will not do any damage. The cost of one case of fluid if you DIY. Do not allow a shop to flush!

Coolant drain and refill will pay the biggest dividend. Again, do not flush; a simple drain and refill with 50/50 mix of Dex-Cool and distilled water will refresh the corrosion inhibitor package (which is what you really want).

Most folks will also recommend a tube or two of Bars Leaks Golden Seal powder (Wal-Mart) as insurance against nuisance coolant leaks.

I would replace both belts at this time.

You might see a small increase in fuel economy with new spark plugs but I doubt you would see a payoff in another 50,000 miles.
No plug wires on an '02 so you can forget about them. As Misfit said, you could pull them and inspect them. 100K is the recommended change interval. On the other hand, if it ain't broke don't fix it. Trans fluid will stay at 100% unless it gets overheated. Factory recommendation says it's good for life under "normal" driving conditions. I do mine at 100K regardless. General recommendation on the cooling system is not to flush. Just drain and refill at recommended intervals or sooner.
Does an '01 DeVille have ignition wires or are the "coils" mounted on top of each sparkplug?
2000 is when the Northstar went to Coil On Plug (COP) ignition. No wires after that.
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