Why is there oil in my coolant resevoir,head gasket leak?

Might have the head checked for warpage and cracks and change the head gasket. The exhaust manifold gasket has no coolant that comes into contact with it.

No! Air bubbles in the radiator is usually caused by a damaged radiator hose, a leak in the radiator, a faulty water pump or there isn't enough coolant in the system. A blown head gasket usually leaks oil into the coolant and coolant into the oil. It may also run rougher if its leaking from cylinder to cylinder.

Hmm try changing the oil, flush and fill the radiator.Then see if the contaminant comes back into the resevoir. If you have a cracked, block/head or a blown head gasket the envoy would have white or blue exhaust coming out and would be overheating since oil retains heat. Some other tell tale signs are little steam will come out of your oil filler when u open it.Your oil looks like chocolate milk instead of regular oil when u check it. Try a compression or a leak-down test to find out if your head gasket is blown. Pull the spark plugs see how they look.

(Contaminated water from rust or mineral? dont use tap water when mixing with the anti freeze)

Hope all this helps you

If you have engine oil in the coolant, probably a bad head gasket leak. Any evidence of coolant on the oil dipstick? A bad head gasket will show up as low compression on one cylinder, or in two adjacent cylinders. So have the compression tested.

When engine completely cools remove coolant from overflow reservoir to the cold mark on the reservoir which is the lowest mark on reservoir. If you continue to loose coolant you may have busted block.

Vehicles: Any with the above symptoms

A cracked cylinder block will cause either:
(a) motor oil contamination of engine coolant
(b) coolant contamination of motor oil
(c) white exhaust smoke, due to coolant seeping into one or more cylinders.
(d) more than one of the above
(e) all of the above

Oil infiltrating into coolant is easy to see - drain some coolant out through the pepcock at the bottom of the radiator, and place it into a styrofoam coffee cup. Oil droplets floating on top of the green (or orange) coolant are easily seen. Or visualize oil by looking into the top of the radiator through the radiator cap.
Coolant infiltrating into and mixing with motor oil will permanently damage the engine (seizing it up through loss of lubrication), and must be prevented.
A leak from above the front suspension is, as physicians like to put it, "nonspecific", with the most likely cause a water pump seal or hose/hose connection.
A leak from near the fire wall will usually be a heater core hose, or hose connection.
A coolant leak on the same side of the engine as the water pump is a leaking water pump or water pump seal until proven otherwise.

To rule out everythng else, here's the 1999 Honda CR-V Troubleshooting Guide for Coolant Loss/Coolant Leaking:

Priority Action Part Type Cause
1 Inspect Water Pump - Worn, Cracked or Leaking Water Pump, or Water Pump gasket.
2 Inspect Head Gasket - Leaking Head Gasket.
3 Inspect Radiator - Leaking Radiator Hose(s).
4 Inspect Radiator Cap - Worn or Damaged Radiator Cap.
5 Inspect Radiator Hose - Ruptured, Cracked or Leaking Radiator Hose.
6 Inspect Freeze Plug - Leaking Freeze Plug(s).
7 Inspect Intake Manifold Gasket - Leaking, Worn, or Damaged Intake Manifold Gasket.
8 Inspect Water Outlet - Cracked, Leaking or Damaged Water Outlet.
9 Inspect Heater Control Valve - Leaking or Faulty Heater Control Valve.
10 Inspect Radiator Drain Pepcock - Loose, Damaged, or Faulty Radiator Drain Pepcock, or Pepcock O-ring.
11 Inspect Engine (DOMESTIC ONLY) - Cracked Cylinder Block Leaking Coolant into at least one Cylinder, causing white exhaust smoke.

CHECK FOR COOLANT LEAKS AROUND THE RADIATOR LOOK DOWN BETWEEN COOLING FANS AND RADIATOR SIDES FOR SIGNS OF ANTIFREEZE.CHECK ALL RADIATORS HOSES AND HEATER HOSES.IF ALL LOOK GOOD CHECK ENGINE OIL FOR COOLANT LEAKS.IF OIL LOOKS LIKE MILK SHAKE COOLANT LEAKING IN CRANK CASE.YOU HAVE A HEAD GASKET LEAK.YOU NEED TO CHANGE OIL + FILTER. GET THE HEAD GASKET FIX.BECAUSE LEAK IN THE CRANK CASE WILL LOCK UP THE ENGINE.IF CRANK CASE OIL LOOKS OKAY.YOU DONT HAVE THE COOLANT CORRECT MIXTURE.YOU SHOULD HAVE 50/50 ANTIFREEZE AND WATER.

Was the smoke white? if so it is probably your head gasket you can still save it if you want as long as the head isnt cracked as well then it probably just isn't worth fixing and from the sounds of it sorry to say but I cant be sure with out seeing it

you could have a blown head gasket and coolant could be leaking into your combustion chamber.
rent a radiator pressure tester and see if the cooling system will stay at constant pressure. If the pressure drops you have a leak, and it could be your gaskets. pretty costly to repair.
make sure you have not blown the seals on the engines water pump. when they go out, the burst disc on the pump open and gush coolant everywhere.

problem could be heads bolts . i put new bolts in put a little sealer on them . make sure your bolt holes is clean free from debris. put a lillte sealer on intake gasket on top and bottom where coolants travel. if all was done . drain engine oil in clean container .set it aside. take radiator cap off .you a coolant pressure rise kit .put a pan under oil pan with drain plug still off .pressure your radiator about 10 psi. make sure you have antifreeze in radiator and engine . when you pressure up to 10 psi look under the car if coolant comes out oil pan. you got leaking head gasket. if not .put oil pan plug back on . put oil back in car . check your freeze plugs also.