While i was doing off road driving a warnning light (a/t oil temp) turn on, i looked underneath the car and i found oil leak drop after drop, not too sure now should I change the transmition oil and filter ? Or change the engine oil? Plz advise

Most used cars come "as-is" or with a limited warranty. Evaluate the price against the cost of needed repairs.A car should start easily and idle reasonably smoothly. Check that all warning lights come on when you turn the ignition and after completely starting the car, go off. Test drive the car for at least 10 miles show any warm-running problems.
Reject a car if:

1. You hear the engine knocking.
2. The oil or coolant warning lights come on or gauge readings are abnormal.
3. An automatic transmission slips on acceleration, grinds or whines, or does not shift smoothly up and down.
4. The clutch shudders or the manual transmission grinds, squeals, or jumps out of gear.
5. There is more than 2 inches of steering wheel free play, roughness when you turn the wheel, or car wandering on smooth roads.
6. The body shakes objectionably at speeds under 55 m.p.h. on decent roads.
7. The exhaust blows blue smoke (oil) or it blows white smoke (water vapor) on a warm, dry day or for more than a few minutes on a cool day. black smoke is usually a minor fuel problem.

Checking out a car:
Brake hard at 25 m.p.h; the car should come to a straight stop. A car that rides poorly on bad roads is because of worn shock absorbers or that has poor braking will need work, but this may be normal for it's age. With the engine still running, look underneath the car/truck for an oil leak. Have a trustworthy mechanic evaluate any such leaks you find (prior to purchase). Check all accessories. Look for lubrication stickers on the door or under the hood for evidence of regular maintenance. Take the car to a professional mechanic, he can detect some problems, evaluate your road-test report, and tell you the cost of necessary repairs. If your state mandates an emissions test, he will be able to tell you if the car will pass or not.

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