I did an oil change twice on my car since i owned it. after both times the motor ran rough and now it starts to shake when i reach about 65 mph. what is my problem

I would recommend having the computer checked for trouble codes next. The codes will help point a mechanic in the right direction for what to test.

Need a professional mechanic to take a ride with you
driving & check all data,especially short term fuel trim.

The O2 Sesnors have less than 100,000 miles?

Do a cylinder leak down test,you have lots of miles
on the motor,so stay with basics & be sure you have
anything left in the motor mechanically

Don't know the car so what controls the idle,& is there an AIC
Valve to clean

change fuel filter and clean fuel injectors.pour a can seafoam to 3/4 to full tank of gas see if it help the problem.

As something to start with, I would check your injectors, do an injector cleaner/seafoam treatment. I would also drain the oil, and check with a magnet to make sure there are no metal shavings running around, and check to see if one of the cylinders has lost compression/the spark plug isn't working.

I don't think the rough running had much to do with oil level, since it started running rough a 2nd time. Check the fuel filter and ignition timing.

I had a similar problem @105k. I had changed the fuel filter but it was still sending all kinds of codes that were related to 2 problems. Long story short, the main problem was a bad trigger assembly in the distributor (rough running) and the other was a loose engine to body ground (engine code issue). Good luck, this worked for me, now 171k.

It sounds like an ignition problem. Make sure your battery is good and connections are clean. I would start by replacing the plug wires and spark plugs. This is a good tune up procedure anyway and will increase your mileage some. Clean or change the air filter. The obvious thing is to make sure the oil is new and filled to the correct level, not overfilled. Your engine will love you. I hope this helps.

Seem like you need to have at-least the two front tires high speed balanced. This shaking at high speed is most likely due to the tire being out of balanced. Good luck and thanks for using FIX YA

spark plugs wires needs complete tune up also synthetic oil change not designed to run on regular oil then check bearings