Ive got a 2003 civic ex and I've been using 5w20 castrol(non synthetic) for 30,000 miles. Ive been waiting for the big guys to come out with a 5w20 synthetic and nothing on the store shelfs. This oil change I went with 5w30 synthetic mobil 1. Any pros or cons or no difference. Thanks this looks lie a great site.Also Ive been buying Honda filters any recommendations?