I have oil in my coolant tank. I was told to replace my Intake manifold gasket. I've also herd about a product called blue devil that fixes these problems without takeing apart the car? has anyone ever used this product? any pros are cons?

I had a 2000 malibu 3.1 and the manifold gasket was leaking. Model years affected, 97-04. Check the recovery coolant tank and if it looks like a milk shake instead of coolant, then you have a bad intake manifold gasket. I replaced mine a few years ago and all was fine. Engines affected are the 2.4-3.1-and 3.5, look very carefully around the intake manifold and you will see it if its leaking! operating the engine with a coolant/oil mix can result in internal engine damage. Replacing the intake manifold gasket should correct these leaks. Because oil will mix with coolant if gasket is bad. Hope this helps you out! Good-Day!

Sounds like a blown head gasket.

you have a blown head gasket.. doesn't have to have coolant in the oil for a blown head gasket... if hoses are rock hard when running then you have exhaust leaking into the coolant via a blown head gasket...

Instructions

1. Removal

Unscrew the bolt that holds the negative connection to the Impala's battery. Set this bolt aside for later use.

Remove the engine cover to access the intake manifold and manifold gasket. Disconnect the throttle body inlet duct from the engine.

Twist off the radiator cap to allow draining of the coolant to flow more smoothly. Place an empty container beneath the radiator's drain plug, and remove this plug. Allow all of the engine coolant to drain into the empty container. Replace the drain plug once you are finished.

Tag all of the electrical wiring and hoses before removing so that reconnection is precise to factory settings. Remove these parts, individually, from the intake manifold.

Loosen the bolts that hold the intake manifold to the Impala's engine block. Lift the intake manifold from the block once all bolts have been completely removed.

Use the flat-head screwdriver to pry the old intake manifold gasket from the engine block. Discard this part once you have removed it.

Clean the engine block thoroughly with the engine degreaser and linen cloth. If necessary, use a gasket scraper to remove excess buildup and grime.

2. Installation

• Coat the top and bottom of the new intake manifold gasket with a chemical sealer so that it bonds to the engine block securely. Position this new manifold gasket so that it lines up perfectly with the cylinder ports of the Impala's engine block.

Place the old intake manifold on top of the newly-installed manifold gasket until it aligns with all of the holes of the cylinder flanges and manifold gasket.

Attach all of the bolts with your hand to the manifold. Once all bolts have been positioned, use a torque wrench and apply 15 foot-pounds of pressure to the bolts to secure the manifold into place.

Reconnect all of the necessary hoses and electrical wiring to the intake. Pour the engine coolant back into the radiator.

Reattach the engine cover on top of the intake manifold and engine block. Start the Impala's engine and check for any leaks around the new intake manifold gasket.

intake or head gaskets for sure

i've nver used them because they normaly wont help.i've heard that the blue devel does
& comes with a guaranty.

Over the years I have seen quite a number of sealers advertised to repair gaskets etc. There are newer ones out that make the same claims (also expensive @ about $100). Though it is possible that they work, I have no idea for how long. As always, the best cure for a cylinder head gasket problem is still to actually do the repair.
Regardless of how you correct the problem, make certain that you drain the oil and filter or you will be looking at a bearing failure shortly.

they a probably referring of you intake manifold gasket but before you do that goo to your local auto zone and buy a bottle of something call blue devil. is expensive like $70 dollars but that works wonders grain some of your coolant and dad the hole bottle on your radiator and run your cars for an hour.
read all the instructions carefully.
this can save you big bucks.
here is a link of some info
CLICK HERE

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.

eBay.co.uk 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

it is EXTREMELY common for the intakes of these cars to leak coolant, internally and externally. What i would reccomend to do is to replace the intake manifold with gm's updated version, which fixes the coolant leaking issue. also change the oil, as some of the coolant most likely found its way internally down to the crankcase. this is really the only way to repair this issue, and it is very common.