5W20 or 5W30 weight oil
 

Not trying to open a pandora's box thread on oil but I do have a question regarding the new 2008 Civic Lx I just got. On my old Honda I used 5W30 Mobil 1 for its life and never had a major problem. On this new one the owners manual says to use 5W20 for all the models EXCEPT the Si...the Si is supposed to use 5W30. Is the Si engine for 2008 so different than the other civics? Since I still have 3 cases of 5W30 Mobil 1 left over do you think I can use them in the new LX after the engines broke in or am I going to damage the engine. Kinda hate using that left over oil in a 6 year old lawnmower :(