Rep Power: 188

Look at attached picture

Apparently Honda says that running 5w20 in 6th gen civics is "acceptable", despite manual saying 5w30 & 10w30

-What could I expect in fuel savings going from 10w30 to 5w20?
-What differences in wear/engine life could I expect?
My engine likes 10w30 Chevron Supreme instead of 5w30... 5w30 causes some upper motor chatter when cold @ certain RPMs..

-Has anybody else done this?
Looks like 'djlunatic' has

 
Rep Power: 313

This has been killed on the forum... use 5w30 to prevent leaks and such... the advantage to 5w20 is slightly better gas mileage... so slight you won't even notice it. 5w30 protects the engine better and is less likely to leak. Your upper motor chatter is probably your valve clearances out of adjustment that is a seperate issue that you should get resolved

 
Rep Power: 217

If it gets too bad, it'll throw a CEL for running too rich or lean. Honestly, I just go by what the manual says to be on the safe side. Like tbohar said, the savings in fuel won't even make a difference.

 
Rep Power: 188

OK thanks. Yeah I suppose it could instead be a bit of piston slap but I don't know how a heavier weight quiets it down. I had my shop do a valve adjustment a while back, the engine sounded the same after the adjustment.