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Discussion Starter #1
i have a 90 deville and i am going to change my radiator coolant soon because it is brown and nasty but i have a few questions. from what i read on the forums i should just drain and refill.

1. my radiator cap seems to be pretty much stuck should it come off easily or do you need to use force and should it be replaced?

2. does the 90 deville have dexcool or green antifreeze and should i use the tablets with green?

3. what would be a good brand of antifreeze to use and how much?

4. is a product such as marvins mystery oil good to use to clean out the system prior to an oil change?
 

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White Diamond '03 DHS (with DTS floor shift)
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1. You must push down on the radiator cap, then turn it. Likewise when instaling it. Note the direction of the arrow and be sure it is in the same direction when it is replaced.

2. Dex came out in '96. You have green. Use the tabs. Especially on the 4.1, 4.5 & 4.9.

3. Most any brand will work fine.

4. Just drain the oil, change the filter and refill it. Oil change is a good time to grease any suspension and steering grease fittings.
 

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13 Challenger RT, 11 CTS Coupe Premium, 94 Eldorado (RIP)
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1. To get the cap off, you need to press down and turn at the same time. Just like a bottle of medicine. Engine should be cooled down before opening it.

2. Your 90 originally came with green. That is what you should replace it with. And yes, use the coolant supplement. Put them in the bottom hose when you refill. Your old coolant is brown because coolant supplement was put in before. That's good.

3. I prefer Prestone.

4. I have used Mystery oil is other engines. I used Oil Flush in the North* when I first got it. I wouldn't use the stuff regularly. But you will probably benefit from using it since your car is a little older.

Just a note...I used the Oil Flush only once. My car is a 94. I have no oil leaks what so ever, anywhere on the bottom of the engine or pan. On the top either for that matter.
 

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Discussion Starter #4
i checked autozone and oreillys for the tabs but cant find then. where can i find the tabs at and how many should i use?
 

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White Diamond '03 DHS (with DTS floor shift)
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I think WalMart has them. My manual said to use 3. Our former guru said 6, I used 4.
 

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13 Challenger RT, 11 CTS Coupe Premium, 94 Eldorado (RIP)
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You can go to any GM dealer's parts counter. I think 5 come in a pack for just a few dollars. Others have used a Bars Leaks product, I believe the Gold. Ranger seems to be following this thread, he'll let you know the exact part #. I have always used the coolant supplement tabs from the dealer since they are right down the road from me.

Oops. Ranger posted at the same time. I thought you used the Bars Leaks, Ranger.
 

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White Diamond '03 DHS (with DTS floor shift)
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The powdered version is simply crushed tabs and will work fine. Use two tubes.
 
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