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Discussion Starter #1
My 1999 Deville base has 98,000 miles, in great shape. Should I take it to the dealer for tune-up, or can my good buddy ase certified mechanic do a good job.
I plan to keep this car until 140 or 150,000 miles.

Thanks for your opinion or experiences.
 

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jameslwalker said:
My 1999 Deville base has 98,000 miles, in great shape. Should I take it to the dealer for tune-up, or can my good buddy ase certified mechanic do a good job.
I plan to keep this car until 140 or 150,000 miles.

Thanks for your opinion or experiences.
You can do a good job yourself, and a mechanic that has years of experience rather than a trade school certificate will do a fine job as well. It's not difficult work at all. Make sure the cooling system gets drained and refilled (use the Search feature above and look for coolant change), plugs and wires swapped, and probably an air filter and trans. fluid change (not a flush), along with a throttle body cleaning and lubricating all the hinges and joints. I think it's worth putting some silicone grease on the door, trunk, and hood seals after cleaning them with mild soapy water. They'll last longer that way and keep out the wind noise better. None of it is too complicated. Maintenance stuff is generally pretty simple. If you're talking about removing the engine for something, I would only trust an experienced mechanic with Northstar experience. For this maintenance cycle, though, anybody you trust will be able to do it just fine.
 

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jameslwalker said:
Thanks for the info. Do you think there is anything I need to do to ensure the longevity of this vehicle?
Maintain the cooling system meticulously. Use DexCool at 50/50 concentration with distilled water, and add the supplement in the hose rather than the surge tank. Replace the cap just to be on the safe side. It's very cheap maintenance. A 15 lb. cap is what you need. I think cooling system maintenance is the most important thing to do.

As far as other stuff, I heartily recommend using OEM parts, especially when it comes to plugs and wires, mostly because they were tested with the Northstar systems and are known to work well. AC-Delco makes pretty good parts anyway. Their air and oil filters test very well compared to other brands. Stay away from Fram oil filters. Many people on various Internet forums, including me, have had bad experiences with Fram filters and they don't test well at all. Other good oil filters include Wix, Purolator Premium Plus, Purolator PureONE, Mobil1, and Motorcraft.

Changing the transmission fluid may not be recommended, but I agree with others that it should be done at 100k. There are some convincing arguments that newer transmission flush procedures are OK, but a high-level expert who used to frequent this forum assured us that it was best to just drain the fluid including removing the "hidden" drain plug, backflush the screens, clean the pan and magnet, and refill the system with fresh Dexron-III. They put Texaco-brand transmission fluid in at the factory.

Check the computer for codes and let us know what you find in there. We can help determine whether any of them are things you should worry about and how to fix them. You can read about how to check the codes here:

http://www.cadillacforums.com/forums/showthread.php?t=53635

Let us know what you find and what other questions you have. You'll find lots of good advice here that will help you ensure your car has every chance to last up to 150k and far beyond. You may find more good information on the GM Owner Center at www.mygmlink.com. It has other tips and recommendations for 100k mile maintenance and all the other maintenance intervals as well.
 

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sorry im a newb, but what supplement in the hose , because i seen before how someone else had said you should actually use some kind of "stop leak" just to add better life to the radiator, is this true ? i bought my car recently , and i see the past owners or owner (who knows) had changed already the radiator and tranny, (oh last but not least any suggestion on a "clunk" i get when u have a heavy foot, i mean when i drive it slow and regular its fine but when im in a hurry on those days it makes that "clunk" noise, would this be the tranny mount or engine mounts gone bad?) so i dont want to end up going through a new radiator anytime soon or having to worry about over heating anytime also..
 

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1998 Cadillac Deville Sedan
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I think you need flush the coolant, change the air filter and check spark plugs
If the spark plugs need to be changed, use GM OEM spark plugs. Someone give me some free Bosch plugs and I put them in then I found they suck.
 

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To clarify, the supplement you need is any one of three things:

1. Bar's Leaks giant tablets (6)
2. Bar's Leaks Golden Seal powder (2 tubes)
3. GM Coolant Supplement tablets (6)

Numbers 1 and 3 are the same thing, just different names. The supplement is added to the radiator hose NOT IN THE SURGE TANK. Its purpose in life is to seal any tiny nuisance leaks in the cooling system that might occur from tiny pores or incomplete seals. It doesn't protect the radiator at all, it just helps seal tiny leaks. If there's a leak and the supplement doesn't stop it, the problem will need to be fixed. It is very important that cooling system maintenance instructions on a Northstar be very carefully followed. Dealerships seem to screw it up all the time, so I don't trust them unless I verify with the mechanic who's doing the work exactly what he's going to do.

At 100k miles, the original plugs have reached the end of their expected lifetime, and they certainly don't owe you anything. Replace them with AC-Delco plug number 41-950 and AC-Delco wire set 748Q for your 1999 Deville and the car will be very happy. I agree that Bosch plugs are garbage.
 

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Cadillac Davelle said:
(oh last but not least any suggestion on a "clunk" i get when u have a heavy foot, i mean when i drive it slow and regular its fine but when im in a hurry on those days it makes that "clunk" noise, would this be the tranny mount or engine mounts gone bad?) so i dont want to end up going through a new radiator anytime soon or having to worry about over heating anytime also..
Sounds like it may be a motor mount.
BTW, I believe your '95 has the 4.9. You can add the suppliment tabs to the radiator (Northstar does not have a "radiator" cap). You may need to crush them to fit them all in.
 

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Discussion Starter #9
The car now has 104,000 miles. I haven't had the 100k maintenance done. The ses loght has not returned. On 700 mile trip NC to MD, I got 28.5 mpg, and on a 1800 mile trip NC to IN I got 27.4 mpg.

Can I continue to run it until I notice a drop in mpg or some other indication that plugs or wires are going bad?
 

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Discussion Starter #10
The car now has 104,000 miles. I haven't had the 100k maintenance done. The ses loght has not returned. On 700 mile trip NC to MD, I got 28.5 mpg, and on a 1800 mile trip NC to IN I got 27.4 mpg.

Can I continue to run it until I notice a drop in mpg or some other indication that plugs or wires are going bad?
 

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I would just do it now, your car osunds like its in pehnominal shape..Better off just keeping it that way. Better to do it early than late. Know what I mean?
 

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I have to disagree with Tombo just a little bit - and it may be just personal idiosyncracy - I'd say your 99 is running like a top ( and it seems to be) with no engine misfiring, no drop in MPG and so on, I'd leave the plugs and wires be.

The only reason I say that is that sometimes, pulling the wires (moreso than the plugs) causes some other connection on the top of the engine to work loose - a vacuum hose, a coolant line or some such trivial thing. And then you have a heckuva time finding it and fixing it.

My 2002 Deville has 134K on it, the plugs have never been changed, and so far as I know, they're doing just fine. MPG is fine, never any stutter or hard starts, runs smoother than a swiss watch.

Don't kick a sleeping dog kind of thing.

BUT, if you feel better doing it, don't let me dissuade you of that, either.

THe cooling system maintenance is a much higher priority - that is not negotiable. Quick, easy, cheap, and has a risk/return ratio much higher than yanking all those plugs out, and dropping around 150 bucks for new ones plus wires, when you may not have had to.

Disagreements with the above statements are perfectly permissable, and valid counterpoints will be carefully considered. :)
 

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Well THIS post is certainly prophetic - I have a '97 Sedan Deville that is rapidly galloping it's way to the geriatric C-note of mileage. It is currently just past 98K and although there has been a hiccup or two along the way, I think that was more a consequence of the 1st owner "lugging" it around town for the first 7 years of it's life, treating it more like a precious faberge egg than a car that was made to be driven. When I got it in 2004 it was in good, but not terrific shape. For the most part, the old guy puttered around Florida doing his chores, rarely taking the car past the old double-nickel and usually not past 30mph.

That situation has since been rectified.

Funny though, what some people's take on maintenance is: while he never missed the usual basic mechanical duties, he NEVER touched the interior. Those leather seats were filthy from ground-in dirt/debris and rock-hard from lack of conditioners. The rest of the inside wasn't any better. I'd venture to say that the carpets had never seen the business end of a Hoover, either. Needless to say, that is not still the case. BTW, if you need a leather treatment, you can't go wrong with a dual product from a company called LEATHERIQUE. It is truly yhe best I've ever used and I've tried just about all of the popular treatments out there.

So, this thread will be used as a benchmark for my own 100K duties. Thanks again guys, for having such a terrific board here!
 

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jameslwalker said:
The car now has 104,000 miles. I haven't had the 100k maintenance done. The ses loght has not returned. On 700 mile trip NC to MD, I got 28.5 mpg, and on a 1800 mile trip NC to IN I got 27.4 mpg.

Can I continue to run it until I notice a drop in mpg or some other indication that plugs or wires are going bad?
You said earlier that you plan to put another 40,000 to 50,000 miles on the car. The plugs will certainly have to be replaced before you sell the car so why not do it now and enjoy the performance of new and properly gapped plugs. Wires too.

Refreshing the coolant is a must-do.

I would recommend replacing both belts; a failure can put you on the shoulder of the road some dark and stormy night. At 100,000 miles, the original belts have given you most of what they have to give.

One other item would be a complete brake fluid refresh. I do that on a calendar basis.
 

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i agree with jimD because They way i see it, why do it at 130K, and have that buck fifty spent on just 20 or 30k more miles and sell it to some bloke. Might as well get the msot out of it, and then not have it floating on the back of your mind. Remember, the caddy enthusiast gets harsh placebo-car troubles from worries about proper maintanence.
 

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Tombo47 said:
oh yea and jimhare.....
I want your Eldo.

Guess I'd better make sure it's locked and alarmed each night, eh?.. :thepan:

If you come to the NJ Owners Meet on 06/17 at Monmouth Battlefield State Park, I'd be happy to take you for a spin..just don't get any drool on it. :)

Now that I've taken the grey paint off the wheels, the chrome rims really shine all the way through.

Here - have some vicarious thrills:

http://www.jmhare.com/Spring2006Detail.htm
 
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