Just had new head gaskets fitted now engine will run until warm and fallter

It somewhat depends on which engine version is fitted but the Vauxhall/Opel ohc engines need the initial angular torquing of the cylinder head bolts and after a warm up and cool down cycle a further small tighten. You will of course have to obtain the exact values from the applicable engine data though this is usually provided with a replacement head gasket.

After thoroughly cleaning of the parts including the female and male head bolt threads. Fit the new gasket and the head, etc. Preferably using new bolts but certainly replacing any corroded or stretched bolts, lubricate the threads and washers and fit the bolts and using a suitable torque wrench tighten in an outward spiral pattern to the initial figure (usually around 18 lb-ft).

Using the same outward spiral pattern the bolts are then further tightened in four stages that is something like 60 degrees + 60 + 30 and then after thoroughly warming up the engine and allowing it to cool for at least 6 hours, tighten a further 30 degrees.

No further tightening is required...

Antifreeze in the oil sounds like head gasket, if it's head gasket sealant, run engine until warm

Lot's of these problems going around. First thing is to locate where the coolant is going. Is it leaking onto the ground or going through the engine and out the exhaust? As for no heat, Check to be sure you have enough antifreeze. Pure water can cause the engine to not warm up and result in no heat. Air in the system can also cause these problems and must be bled out through the air bleed screw on top of the engine. On most of these cars it is towards the passenger side front on a metal pipe. It's a funny looking fitting with a flat head screw on top and a hole on the side. With the system full and the car running, slowly open the screw until bubbles come out and continue to bleed until you get no more air out. Let the car run to reach normal running temp and try bleeding again and again until you can't get any air out (they're funny that way). If you can not locate coolant leaking onto the ground it's due to a blown head gasket or a cracked head.

What happening is you have a bad head gasket or its starting to go bad. As long a little oil is getting in to cylinders causing that smoke once it warms up that gasket is expanding thus the smoke stops. I would keep an eye on oil levels if it gets milky replace gasket asap. Could also be intake gasket but highly doubt it this sounds like a worn head gasket.

Have you checked to see if your fan is working ?
After performing your repairs, did you bleed the coolant system ? One way is to run vehicle with heaters running to make sure that air in the heater core / hoses is bleed.

Unfortunately there's no way to tell until you pull the head off. if the gasket has failed you'll nee to get the head checked for cracks and flatness anyway (and possibly skimmed flat) and if the head comes off you have to replace the gasket anyway.

With overheating, the most likely situation is that the head has warped slightly causing the gasket to fail. If so, the head gets skimmed flat before fitting a new gasket. Note that on many modern engines it's vital to use new head bolts upon reassembly; your Oldsmobile dealer can tell you if this applies to your model.

The head gasket goes between the block and the head, and seals the combustion process, and cooling water, and (if oil is pumped obove the heads to valve components) oil pressure.

Intake gaskets seal between the intake manifold and the head, and seal against intake vacuum, and in many cases, coolant.

A badly blown head gasket will so destroy compression in the cylinder that you can hear uneven cranking as that cylinder comes up on compression, kind of a “whir, whir, WHIR, whir, whir, WHIR, whir” with the capitalized whir being the engine spinning much faster due to no compression holding the starter back.

You will never be able to hear a problem with an intake manifold gasket until the engine actually starts to fire and/or run.

Sounds like you have a bad head gasket, Some simple tests at a repair shop can verify this.

No use putting any money into this until you verify the integraty of the engine

These Engines use a plastic intake manifold with rubber gaskets sealing them to the cylinder heads. The workshop I worked for had this problem & went through heaps of different scenarios to work it out. Turned out the intake manifold gasket had gone hard & was leaking until the heat of the engine had re-created the seal, which was taking anything from 30 seconds to a minute. It took heaps of testing to arrive at this conclusion & once the gasket had been replaced it was as good as new.

U have a leaking cylinder head gasket, both symptoms fit perfectly.