Whats a good synthetic oil for manual trans and gear oil?
 

Just wondering what you guys use in your manual trans.,also I just changed my oil and I am using CASTROL 10/3O engine oil is this a good brand I am asking cause the car was used and I do not know what was oil originally in the engine
My car is a 2003 accent 1.6 ,71000 miles.

People have different opinions on what is a "good oil", especially for the engine. It's hard to mess up the trans as long as you use the manufacturer specified oil because manual trans oil does not have a relatively hard life.

As far as the engine goes, the bigger question is how often the oil was changed before, and how dirty the engine is on the inside. You can see this by looking inside the valve cover and make your own evaluation. If it's clean enough, it's ok to use a synthetic. Your Castrol 10/W30 is much better than I would ever use.

Certainly, most oil is better than the stuff they use at the Jiffy Lube. I use the Super Tech stuff from Walmart, sometimes I get the High Mileage stuff. I just change it when I think it looks dirty.

You can judge how good an oil is by looking at and comparing the service ratings, stamped on the label of the oil. Look up what the various oil ratings mean on the internet.

the castrol stuff is fine, i use their synthetic myself. i really noticed a difference with the trans but not the engine. i just buy the stuff when it goes on sale and use an extended drain period of 7500-10,000 kms.