Would it be worth to fix a 95 nissan maxima with a cracked head gasket and 97 thousand miles on it

Which gasket is it you are talking about ... a cylinder head gasket or a water pump gasket?

A cylinder head gasket replacement isn't straightfoward or cheap to do and requires a lot of technical ability and tools... In the UK a cylinder head gasket replacement would cost about £1000 - probably the same in US dollars

If it is the cylinder head gasket, try a special additive in the coolant system. The images below are generic. You will find similar products in the USA:




For radiator/block sealant have a look for something like:



Most car accessory shops will sell similar products.

However, if you're determined to replace a gasket yourself, it's a workshop manual you need.

http://diyservicemanuals.com/nissan-maxima-service-repair-manuals

Haynes Nissan Maxima Print Online Repair Manuals

Unless it has been replaced recently, I would advise changing the crank seal, cam seals, tensioner and belt, and water pump while you are there.

You might have a cracked timing chain cover, blown head gasket, cracked block, or bad radiator if it has a built in oil cooler. It's hard to say without a cooling system pressure tester.

does car turn over or is it seized-if seized might be better to look for a new ,rebuilt or bone yard motor depending on ur $$$ status---if turns over coolant gets into oil by either bad or cracked intake or intake gasket----blown head or head gasket---cracked cylinder these are the cuses that oil and coolant mix and neither is a simple fix will need to pull motor apar for repair

The big question is - is the car worth fixing to you.
If it is paid for, and you are ok with driving it for another 2 or 3 years, it may be worth fixing. If you are getting tired of driving it, maybe not.
You can find out what it is worth and then decide.
Oil in the coolant with a manual trans car usually means oil from the engine. That can be from any number of places, from a head gasket, intake gasket, a cracked head, and so on.
It may also have an engine oil cooler that runs thru the radiator that could be leaking somehow.
Oil in the coolant is not a major issue by itself, but if it is coming from a gasket or crack it will get worse and cause other major problems over time.

Fig. Cylinder head bolt loosening sequence - Altima & Maxima 3.5L engine

Install the cylinder head bolts and torque in sequence as follows:

1. Step 1: 72 ft. lbs. (98 Nm).
   
2. Step 2: Completely loosen all bolts.
   
3. Step 3: 26-32 ft. lbs. (34-44 Nm).
   
4. Step 4: plus 90-95 degrees clockwise.
   
5. Step 5: plus 90-95 degrees clockwise.

Fig. Right cylinder head bolt torque sequence- Altima & Maxima 3.5L engine




Fig. Left cylinder head bolt torque sequence- Altima & Maxima 3.5L engine

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

to "fix" a head gasket requires taking off the cylinder head and associated compnents, getting the cylinder head serviced to ensure flat surface and no cracks, reaplcing the head gasket, and reassembly ensuring the proper torque of all bolts, especially head bolts........what makes you belive the head gasket requires fixing

Exhaust leak?

Simple thing to test first would be to pressure check the radiator cap. Next would be to check for combustion gases in the radiator indicating a leaking head gasket.  It is an aluminum head and iron block engine and there is a possibility that antifreeze anti corrosionpackage runs out due to over age then fails due to too long in the engine it results in galvanic corrosion at the head gasket-commonly resulting in a failed head gasket.  There are other engines that are vastly more prone to this than the maxima engine.  If there is a leaking head gasket the gases could rise to the top of the system and block the water flow into the heater.  Listen for gurgling sound in the heater.

head gasket my 95 model did the same thing