How do i fix an oil leak?

How could you tighten the screws and have them loose again? That does not make any sense. Get specs and use torque wrench this time.

no oil on dipstick is a very BAD THING make sure you have oil in the motor before you do anything else!!! or else it can cost you a motor if you did your own oil change,,, did you put oilpan plug back in? did you tighten the oil filter? did you put 5qts oil back into motor? there SHOULD BE A READING ON THE DIPSTICK. new oil looks almost transparent on the dipstick. try rubbing your finger on the dipstick to check for oil presence. look real close at the dipstick before you start your motor!!! if you added 5qts oil it went somewhere,are you sure it went into the motor? if no oil in motor there will be loud knocking from the motor. hope this helped you save your motor!!!!!

The most likely cause would be the valve cover gasket.It is a relatively cheap and easy thing to fix and can be done at home . Hope this helps.

White smoke means water getting into cylinders. Usually leaking head gasket, or possible intake manifold gasket if the manifold is heated with water! You need to see your service people again. Weather conditions should never cause this problem. The oil leak might be fixed by tightening all of the perimeter bolts on the oil pan.

depends where the oil came from.of it has leaked down from a valve cover gasket,that is not hard to fix.if it a leaking valve seal that is expensive and if the head gasket is leaking,expensive.look at the outside edge of the valve cover,and check the edge for oil.if there is alot of oil,by the time the plug is unscrewed oil can go inside.the oil would burn off,so if there is oil inside it is dripping down probably from a valve seal.take off the valve cover and inspect the seals they are probably no good.there are 2 seal sets,one is in the valve cover,and that results in oil on the outside of the plug,and the actual valve seal which results in oil in the inside of the engine.

i have a mazda mpv 2001 , hold lihgt is blinking , how can i fix it ?

If oil was just around the plugs you have a oil leak somewhere . If the tip of the plug that goes in the motor is covered with oil it is either worn valve seals or piston rings. If it leaking oil look at the valve covers this is on of the most likely place for oil leaks.

Change your piston rings. Check your compression. I'll bet that cylinder is more than 15% lower that spec.(all the others in the motor if its a older one.)If you just did that you will see some untell the rings seat. (if you made sure all the new ring gaps are not lined-up in the same place).
If the oil was on the top of the plugs you fix whatever is leaking on them. If it was on the electrode, the above is true. 

Hi bravo956
i also have the same problem regarding the oil leak. this is due to the spark plug gasket leaking and you will need to replace them. they are circular gaskets about 1.5 inches across that fit to the underside of the rocker covers and prevent oil from seeping down the long spark plug hole. when i investigated my leak i assumed it was just the rocker cover gasket that was leaking but once everything was removed it is obvious.

if the needle is on or around the letter N then thats normal. you can also change the oil sending unit. as far as the engine light once you change the EGR valve and the EPT sensor the engine light should go off