Question about 1996 Chevrolet Monte Carlo

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Oil in over coolant tank

I have oil in my coolant overflow tank. I am running green coolant in a car that came with dexcool orange coolant. This is a '96 monte carlo.I have within the past two years had the intake gaskets replaced, water pump, and radiator replaced. Why do I have oil in the coolant overflow tank again? Are the intake gaskets shot again?? Should these need to be replaced again this soon???

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    Car is a Renault scenic S Reg with the 2 litre 8Valve engine.



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Since you are running green coolant in a car designed for dexcool that may have contributed to a leaky intake gasket and/or head gasket. dexcool was specially formulated to run in the GM vehicles because the gaskets and seals can be easily distorted when the wrong chemicals are soaking them. oil in the coolant is usually either a head gasket or the lower intake manifold leaking into the cooling system. also if the intake gaskets werent done properly that would cause oil in the coolant as well. i suggest you take your car to a reputable shop and have it tested for a headgasket leak and to have the lower intake inspected.

Posted on Feb 17, 2009

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If there is oil inside the coolant liquid that is the head gasket.

Check first if oil can leak into the coolant tank from the cap.

Usually when you get oil into the coolant liquid you have an head gasket problem, do a compression test, or buy the home tester below. Guides - HOW TO TEST FOR A FAILED HEAD GASKET
Head Gasket or Combustion Leak Test Procedure (Gasoline Engines Only)
Blown Head Gasket? how to check

Posted on Feb 17, 2009


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Why does my 2005 impala leak dexcool like crazy, which throws my heat off.

There are several areas that these cars have issues with coolant leaks first off is this car leaving a puddle of coolant on the ground?

If not check the oil and make sure after it's been run awhile that the oil doesn't resemble chocolate milk if it does then the coolant is leaking internally and could cause sever internal engine damage if not addressed promtly. The engine damage occours due to pitting and rusting in the lifters rod/main and cam bearings, oil and water don't mix. Check the oil after the engine has been run a while since if the car sit's the oil and water will separate and the oil may look ok other then being overfull slightly.

Another area that is comon for leaks is the overflow tank if this type has the pressure cap on the tank I have had several bad tanks like this.

The water pump may be leaking out the weep hole located behind the pulley and should be checked with a pressure tester,light and a mirror.

But probably the most comon leak of all is the intake gasket leaking out both one or both ends. Dex-cool adds to the likely hood of these gaskets being the problem since it is citrus based and has had huge classaction lawsuits against GM in the past. Since this car is no longer under warranty the best advice I can give you is to flush out the dex-cool and replace with a good quality 150,000 mile 5 year green like Peak antifreeze or equivalant. But first find the laeak and have it repaired.

Jan 03, 2012 | 2005 Chevrolet Impala

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, I bought an Oldsmobile Achieva 1996 and wanted to know what kind (color) of coolant do I use?

should be a sticker near the overflow bottle, if it says dexcool you need the orange stuff.
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for the best results use distilled water for the mix.

if there is no dexcool sticker you can run the 50/50 green such as prestone extended life

Sep 18, 2011 | 1996 Oldsmobile Achieva

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Do I add anti freeze to the radiator or the lid tat says coolant


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Low coolant light come on and off while I am driving or just starting. There is plenty of "water" in radiador and overflow tank.

Be sure the right coolant is in the car, orange colored Dexcool. I fthats good, then replace the coolant level sensor, in the right tank of the radiator. near the headlight. Of some cars its easier to replace the sensor if you take the headlight out.

Jun 05, 2010 | 1995 Oldsmobile Cutlass Supreme

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Mar 19, 2010 | 1994 Cadillac Seville

1 Answer

What type of coolent for 1999 chevy astro

Hello! Your van most likely still has the coolant that was in it from the factory - which would be DexCool. If you can see it in the coolant overflow, and it is orange-ish in color - it's DexCool (or possibly a DexCool-friendly brand). I would suggest a full, and thorough coolant system flush - and then refill with the green stuff. If your van does have DexCool - you CAN NOT mix it with anything that does not implicitly state that is compatible. If you do - it will harden and congeal and ruin your coolant system - and perhaps even your engine.

Hope this helps!

Sep 18, 2009 | 1999 Chevrolet Astro

1 Answer

Radiator is empty

Always fill you radiator & resevoir with a 50/50 mix of coolant / water. Your vehicle should have dexcool which is a red/orange colored coolant. You can buy a universal equivalent which is premixed and is yellow (not green). It is safe to add universal coolant but not green antifreeze. Premixed (it will say on jug) would be your safe bet. Fill the radiator, add to overflow tank to full cold line, run vehicle until fully warmed up. Let cool back down & then recheck.
Don't forget to check for is not normal to have your coolant get that low. You likely are leaking coolant.

If this helps please rate me!
You can do it.

Mar 19, 2009 | 1999 Chevrolet Blazer

2 Answers

Oil in the radiator

are you sure its oil in the antifreeze? oil is brown. your van should have dexcool wich is orange, not green.(looks red sometimes)check the coolant again and check the oil. if it looks milky or foamy, there is coolant in it. sounds like it may be a blown head gasket. not good. stop driving it if you want to save your engine. you need to replace the head gasket/s, and flush the cooling system.

Jan 17, 2009 | 1997 Chevrolet Venture

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