I have a 91 Honda civic 1.5 l engine automatic.with a oil problem?

I have a 91 Honda civic 1.5 l engine automatic with 125,000 miles.with a oil problem i just recently switched over to castrol syntec blend and before that i used normal penzoil 10w 30 now i use castrol syntec 10w 30.i did the oil change and whatever but the drain plug seemed old .now there is a little oil under the car (on the oil pan) and it slighty leaks.do you think it is the older looking oil drain plug?I just did my oil change about 900 miles ago.should i wait till 1500 to change the plug oil and filter?or just keep adding oil till 3000 It is practicly nothing that it leaks like the size of a 50 cent coin once in a while.like the size of a dime once every two days.on the oil dip stick where should the oil be up to?My friend has a 97 Honda prelude and he put castrol syntec when he hit 100,000 he told me that he also his car leaked when he made the transition to syntec.he also said it burned a little fast till the car became accustomed to it Thank you ALL!I have a 91 Honda civic 1.5 l engine automatic.with a oil problem?
On all Honda's that year a crush washer is used to seal the drain plug. They can be reused a few times but more than likely it needs a new one. If your drain plug looks worn replace it too. If by any chance the threads are stripped out, you'll need to replace the pan or get it repaired. I would advise going to a Honda dealer. Plus I would advise using Valevoline 10-30. Honda builds the best motors in the world. That means using basic high grade oil and the cheapest gas you can find. Never add any additives to the oil or fuel. Regular tune ups and valve adjustments plus 1 or 2 timing belts and water pumps will take that engine well over 200K miles. Don't forget air and fuel filters on tune ups.