How do I clean the white substance out of my oil tank

If you have a "white substance" in the oil, it is likely that you have a blown head gasket. If that is the case, cleaning it out will do no good unless the problem is fixed.

You could change the oil, and see if it returns.

Fix the failed gasket so you stop getting coolant in your oil and of course change oil. Change oil again at half the regular oil change interval and then go back to regular intervals. Should be fine at that point.

is head gasket fix expensive

It will certainly be several hundred dollars. If its not leaking too badly you might fix it at least temporarily with one or two applications of Bars Leak. It's a cheap fix if it works and can't do any harm.

Munron its not leaking at all so is that a good thing

Yes, that's a very good thing. If the gaskets aren't leaking leave them alone.

So will a tune make a difference munron

The coolant temp does not go to hot is that good when the oil may be mixing with antifreeze

What exactly is the problem with your car? Is there coolant in the antifreeze? If so it is likely a failed head or intake gasket. If it is not coming up to temperature it could be a failed thermostat that is stuck open. Check your coolant level first though. If the system is not full the car will not operate at the right temperature which is very important. It will either over heat or not heat up due to air in the system and inadequate coolant flow.