Synthetic oil change every 3k?

[georgecastaneda]

guys i gotta a used motor in december. all i know is that the motor have less than 100k and it's actually running with castrol edge full syn 5W30 but somebody else told me to put 10w30 should i do that?
i live in new jersey and there pretty freezing on winter and very hot summers

any answer will be trully appreciated

 

[speed6lukasz]

for me its every 3 to 4 k and i use castrol edge synthetic 5-30w...