Which weight motor oil for both Kia and Subaru?

I've got a 2007 Kia Spectra (~6000mi) which calls for 5W-20 and a 2003 Subaru Outback (~100,000mi) which calls for 5W-30. I change my own oil and would prefer to just have one stockpile of oil, all the same weight. Think either weight would be any better than the other for both vehicles?Which weight motor oil for both Kia and Subaru?
Use the manufacturer specified oil, It is there for a reason. Though 5w30 wont hurt either engine it pretty much standard for all engine but diesel. Try to stick to mobil 1 and castrol most people agree they have the best additives. Use a high quality filter. Change your oil every 3000 (5000 if you use synthetic). Going beyond that isnt a good idea,the filters no matter how good cant handle it; even newer oils that advertise 10000 or 15000 miles suggest changing the filter every 3000-5000 miles. Which of course means partially changing the oilWhich weight motor oil for both Kia and Subaru?
5w-30 is fine ,,and better for ur engine,,,5w-20 is very thin,,and only used to boost fuel milage a tiny bit....use mobil 1 and a GOOD (napa gold) oil filter,,,and just change ur oil once a year..or 15,000 miles,,,IT IS THE BEST