What viscosity oil do I need?

I drive an '01 Ford Sport Trac with 205k miles. Someone recommended that I start using thicker oil since my engine has been well broken in. He said that the regular 5W-30 would probably be like water and not lubricate it well. Last time I changed it, I used 10W-30. The truck has ran fine, but I've noticed several spots in the driveway where oil has been dripping. Now that summer is almost over, I don't want to use thicker oil because it can clog up inside the engine on cold nights. Suggestions?

Find out where the oil leak is before it gets to be a serious issue. The 5w-30 oil should be just fine to lubricate the engine. In reality the thicker oil can cause more wear at start-up because it takes longer to pump up. Although I don't think 10w-30 is much change from stock so it probably is fine. The 10w-30 won't clog up anything in the winter, it will be just fine as long as it's changed at recommended intervals.

Something like Penrite 20w50 should be fine for that many miles

Whomever told you that 5W-30 is like water and will not lubricate well has no clue what they are talking about. Ignore that person. Your vehicle calls for SAE 5W-30. As you have over 200,000 miles on it I would recommend you switch to SAE 10W-30 High Mileage oil as your engine is worn after this many miles. Any major brand is excellent. When it is cold it is 10 weight so do not worry about is clogging anything as it will not.

Some people are right here. That first number is the winter weight this modern oil is engineered to work like thinner oil at a colder outside temperature. So say it is 20 degrees outside and you have the 10w-30 and the engine has sat overnight. The oil upon start up will have the same viscosity as a 10 or pretty thin but once the engine reach a higher temp the oil actually thickens to the 30. The problem with these thinner oils is they don't stick to the metal parts to well thus causing more engine wear and tear car manufactures use this 20 weight to save on fuel thats it by your truck running to spec a 10W-30 is about right for a new car but you are noticing oil leaks. This is common they could be simple oil pan gasket or valve gasket leaks soon enough they may get worse. But running a thicker oil may also plump of the old gaskets it isn't like getting new gaskets but it can help. You can try going up to the 40 weight but once you are in that territory a gasket needs to be fixed. So if you live somewhere that in the winter gets below 20 degrees pretty often look into the 5W-40. If it rarely gets to freezing or hovers right around that yeah you can get away with th10W-40. If the temp never gets below 40 where you live the the engineered stuff won't even activate it takes temps down around freezing to thin out.