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2002 Deville, 1990 Deville
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Discussion Starter #1
Sorry for not being more specific in my title, but I have many questions that I hope experience from the readers will help with. I'm new here so be nice !! Just bought a 02 Deville, 24,000 miles. I had and still have a 90 Deville. One of the best cars I ever had. Now for my questions.... Opinion.... oil changes every 3000 miles, or go by the computers decision? Opinion.... What kind of oil? I usually use Pennzoil. My big concern and I'm sure the subject comes up many times... DEXCOOL !! The car is in the shop right now because of a leak. I thought it was transmission fluid (next question) but the Caddie garage said the water pump gasket was leaking and fixed it. I asked the service manager (knowing he can't very well pick on a GM item) his opinion on Dexcool and if when the warranty is over if I should switch to the green old reliable stuff. Of course he said there is no problem with Dexcool. Well a gasket leak on the cooling system on a car with 24,000 miles on it makes me wonder how good it is. Any thoughts ?? And finally, when I discovered the fluid on the garage floor, I thought it was oil. I checked the oil in the car and it was fine. I checked the trans fluid and there was none on the dipstick. So I thought trans leak. the Caddie garage said the fluid is fine. According to them the fluid has to be to operating temp to get a read. Well than how come there is a cold level reading on the stick?? The fluid was well below the dipstick.
Any help would be great. Thanks, Boilerman
 

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White Diamond '03 DHS (with DTS floor shift)
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:welcome:
Follow the OLM (oil life monitor) for oil changes. 3K may be too long for short trips in cold weather. The computer is smarter than you (we) are.
Stick with Dex. It is fine. The water pump cover gaskets were a problem and have been redisigned. That was your problem, not Dex.
Trans fluid should be checked hot, idling in park.
Go to the top left of this page and click on Technical Archives. Most of your questions, and then some will be answered there, and in more detail.
 

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03 escalade
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Ranger said:
:welcome:
Follow the OLM (oil life monitor) for oil changes. 3K may be too long for short trips in cold weather. The computer is smarter than you (we) are.
?
I thought the OLM reccomends oil changes far less frequently than 3k..... closer to 5-7k...? Do I remember incorrectly??
 

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1998 Cadillac Deville
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484 Posts
Swine said:
?
I thought the OLM reccomends oil changes far less frequently than 3k..... closer to 5-7k...? Do I remember incorrectly??
The computer does it based on conditions, so if the conditions and stress, temperature etc. make the oil need to be changed at 2500 miles its will tell you. On the flip side it could have the oil go for 12months. Just how the cookie crumbles. :)
 

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Cadillac Owners Connoisseur
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Swine said:
?
I thought the OLM reccomends oil changes far less frequently than 3k..... closer to 5-7k...? Do I remember incorrectly??
No, you are correct. It will tell you to change it somewhere between 3000 and 12500 miles, depending on the year of your car, the type of oil recommended for it, the way you drive it, the temperatures, and other factors that I don't remember. Nobody has ever had an engine failure due to following the recommendations of the OLM and using motor oil of the weight and type recommended. Most Northstars use conventional oil. The VVT engines require synthetics for the hydraulic cam pump, but there is really no reason to run synthetics in non-VVT Northstars, despite what the Mobil1 bottle tells you. Just use a good filter like an AC-Delco or a Wix or Purolator PureOne or Premium Plus, or a Mobil1 filter. Frams suck.

You can verify whether or not the Oil Life Monitor is a valid indicator or not by having a Used Oil Analysis done when you get the oil changed. Therfe are lots of labs that will do this for you such as Blackstone Labs, Dyson Oil Analysis, etc. Do a Google search for "used oil analysis" and you'll get plenty of results. I would bet that the UOA will come back showing that the oil is protecting and lubricating just fine when the OLM says it's time for an oil change. So far nobody has done this, but I'll do it next time I do an oil change (probably in the spring, I'm at 79% oil life remaining) and I'll be glad to post the results no matter what they show.
 

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2002 Deville, 1990 Deville
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Discussion Starter #6
Thanks to all who helped. I feel much better knowing there was a problem with the gasket. I was worried that is was the Dexcool.
Also Great idea about oil analysis. We do this where I work on equipment. It really tells the tale of what's up. I'll do it !! By the way, I just had my oil changed at the Caddie dealer for the first time since I had the car and the oil life monitor said I had 65% left. But, my reason is I had the car in for warranty service so it just was a convenient time to change it. Also I just got a call from the Caddilac shop telling me they need the car 1 more day !! The power lumbar switch did not work and they broke the new one. Oh well it's one more day 1 get to cruise in my 90 DeVille !! Thanks again and more input on this would be great.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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The "problems" you most likely hear about Dex is from Chevy truck guys. Silicated green coolant plates the water jacket with silicates, so if the coolant level runs low it will not rust (cast iron blocks). Dex does not. They don't maintain the cooling system and it gets low. Now rust forms in the high points and when they get the RPM's up, coolant sloshes through and washes the rust out, only to have the process start all over again. Eventually, the rust particals settle in the radiator or heater core and cause a problem and Dex-Cool takes the rap for it. None of the problems have ever been associated with Cadillac or an aluminum engine to my knowledge, nor have any of the class action law suites been won, unless they are still ongoing.
 

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2002 Deville, 1990 Deville
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Discussion Starter #8
Ranger,
Thanks for the input. On one hand I hear Dex horror stories. On the other hand I keep thinking if Dex was as bad as I hear, GM would have changed it by now. What you say makes sense. There is a radio show out of New York called the car doctor. His take on it is any leak in the system makes Dex acidic and then proceeds to attack gaskets. Due to the fact I listen to the car doc's show quite often his take on it had me worried. Most callers to the show are encouraged to switch to the green anti-freeze after the warranty expires. As of right now with your input I'll just flush and fill with Dex again next year when my DeVille is 5 years old. Mileage will be no problem. I'll most likely have about 37,000 miles on the car by then. Thanks again.
 

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White Diamond '03 DHS (with DTS floor shift)
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Well, from what you say, I am not impressed with "The Car Doc". Dex is infact acid based and should NEVER be used straight, but I doubt that air contact has anything to do with it "attacking" gaskets. As I mentioned, green coolant plates the water jacket so once you use it, you can go back to Dex but you can never go back to 5 yr changes. You can always change it at 4 years to be a little safer if you wish.

GM and Texaco jointly develpoed Dex-Cool. I think you are correct in assuming that if there where a problem with it, it would have been replaced many years ago.
 
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