1989 Geo Metro • 398,740 miles

When my Geo Metro gets to about 70mph it starts to shake. Feels like it's the engine because the steering wheel is what really shakes. It's a 1989.
September 1, 2011.

Have the tires rotated and balanced.
With the mileage, if you have not checked the suspesnion for loose ball joints, tie rod ends, bushings, wheel bearing, etc. There might be soemthing that is loose and needs replacement.
As far as the motor, tere might be a cylider that is weaker than the others. Howeber, if this were true, you would feel it at lower speeds as well. Unles you are revving it higher at high speed. Check the fuel pressre, plugs and air filter.

I also think my oil is burning up because it's disappearing but leaving know oil stains on the ground. And my coolant is doing the same. But it's a car I love and want to keep it even if that means a new engine.

Sep 1, 2011.
Oh and there is a open gash in the left front boot of my car.

Sep 1, 2011.
The anti-freeze and oil are signs of a failed head gasket. This will cause misfiress and loss of compression which will cause engine vibration and lost performance. Generally people think the heaviest load on a motor is from stopp to start. While thiss is true air drag from higher speed is very heavt and increase exponentially with every MPH. I used to race motor cycles and going from a bike without afairing, (body work for aero dynamics) is a big deal. Adding a full fairing that is aerodynamic will gain10-15 MPH.

As far as the CV axkw boot. That is going to give the worst vibrations from 40 -45 MPH. Without the boot means no grease because it spins so fast the grease is thrown aot very quickly fomcentrifical force. This creates play in he axle wlmowt immedialty as they not only see high rotational forces, but up, down and some back and forth mtion tht they fail very quickly.
So you have at least the 2 problems that are the worst to fail as far as vibration. I imagine the shaking is pretty violent and will get worse rapidly.
A head gasket is not hard to do, but there is certainly a lot of damage to the motor from the oil being des-placed with anti-freeze and low levels of oil. So, the best bet is a used motor. The metro is a 3 cylinder, (if I remember correctly) and will be nearly impossible to find.
If you seek out a used motor, you might look into a European, (whch you can find in Canada), or a Japanese importer which co by the acronym JDM. They will have to special order it, nut it can be found.
I cannot say much for a re-build as there is little in the market as far as parts and cross reference of what will work from other cars. This is some thing that you will have to find a remanufacturer in Canada.
You have some Internet and phone calling ahead of you, but keeploooking if you realy like the car. You may find that a 4-cylinder from Erope will fit or try EBay here and the Europan EBay.
Good luck and let me know how it goes.