Spark Plugs

[fivepointohman]

Changed my plugs today. they had about 30K on them with hard driving on a 122K motor... Car had plenty of power, Just changed them cause the car has been sittting for 6 months and I am taking it from NY to SC next week. Changed the wires as well. The plugs were factor 41-950 AC delco Platinums. The old plugs had alot of white deposits on them, almost like a corroded or ashed up look. I know the previous owner ( my friend ) used a crap load of Fuel cleaners and additives, which I know leaves this deposit behind. I been using 89 in this car, should I go higher to keep the engine and head gaskets happy? I was concered about collant being burned and that being the deposits. But I dont think that is the case I think. Just askin everyone opinion.

[TDK]

Our '94 Deville Concours turned about 210,000 recently. Still running great upt to 125 !

Dang good stuff:

Drips a bit of oil, but still less than a quart low after 6-8000-miles at oil change

It may have had plugs around 125,000 or so. No problems, I just thought it might like 'em.

Never changed plug wires or any other engine part, or any adjustment that I can recall.

Changed the tranny fluid around 125,000. Never opend up or adjusted.

Thought about it, but never have cleaned the mouse holes, throttle body or any other orifices.

Changed the coolant once at perhaps 180,000 to Prestone multi-purpose yellow.

Never has had any electrical problems.

Of course it always starts (I would never would assume otherwise).

I don't recall changing any light bulb, ever (and they seem to work OK).

Never have used any fuel additive or cleaner (they can be tough on the fuel pump as well).

Less than good, but not too bad anyway:

Tranny has the 45-50 mpph chuggle, ever since about 60,000 miles.

Added freon once I think. The HVAC thermostat has to be set lower than normal.

My boss changed all the belts before I got it

Installed passive struts in front and aligned it once.

CD-eject in dash crapped out and was changed to a new head unit.

Had to swap window motor from drivers to rear.

Had to fix lock on passenger door.

Replaced a windshield due to rocks. Never has leaked anywhere.

Never changed any exhaust etc, but w/o leaks it still does have a throaty rasp and snarl.

Changed the air filter once I think, the oil filter was changed every other oil change.

Had some brake pads changed once.

Perhaps one set or tires. Nothing fancy, just the right size Kelly-Springfields or thereabouts.

Had to replace the chrome wheel centers. Lost one of the rear wheel skirts and tossed the other to match.

One rim may have a slow leak due to some inside chrome peel, but the rims are still round and all OK after a LOT of gravel and near off-road.

Son changed the battery a few months ago for the first time in 7-8 years.

If I forgot anything, then it must not have been too important anyway.

Oh yes, Fuel! Almost always use cheapest gas grade around and can't tell the differance. However, if I'm gonna need it all for some highway in the triples, then I have sprung for a tank or two of premium.

How does it run so well? Maybe run as much highway as possible compared to city. WOT at least every few hours regardless.

and... get a good one to start with.

Good Luck

[MAC]

Changed my plugs today. they had about 30K on them with hard driving on a 122K motor... Car had plenty of power, Just changed them cause the car has been sittting for 6 months and I am taking it from NY to SC next week. Changed the wires as well. The plugs were factor 41-950 AC delco Platinums. The old plugs had alot of white deposits on them, almost like a corroded or ashed up look. I know the previous owner ( my friend ) used a crap load of Fuel cleaners and additives, which I know leaves this deposit behind. I been using 89 in this car, should I go higher to keep the engine and head gaskets happy? I was concered about collant being burned and that being the deposits. But I dont think that is the case I think. Just askin everyone opinion.

With another Eldorado I use to own, which now has almost 230K, the wires are still original. And I believe the plugs went about 130K. The dark cherry Eldorado below has 105K and I believe the original ACDelco plugs and wires, particularly since the first maintenance for the Northstar was generally at 100K--I bought it when it had about 90K. I'm going to inspect a few plugs over the weekend because it seems to be missing at idle from time-to-time so I suspect the plugs. Also, you can run 87 octane in your car so no need to buy 89 or 92.

[BodybyFisher]

If they were platinum plugs they are good for 100K. White deposits are normal, see this article and see if you can see your plugs

http://www.centuryperformance.com/spark-pl...ng-spg-192.html

I do not believe that the octane rating has anything to do with keeping the head gaskets happy.

[Marika]

http://www.gnttype.org/techarea/engine/plugs.html

You can see images and explanations here as well.

[fivepointohman]

Thanks everyone for the explanations!