5-20W oil for 2004 Explorer?

My son got a 2004 Explorer some time back and it had an oil change right before he got it. After 4000 miles I decided to change the oil but did a dumb thing(maybe). Not having an owners manual I put 5-30 Valvoline sythetic in it like his older one, without doing proper research. I ordered him a factory service manual set and was shocked to see 5-20 recomended....Any problems here with a slightly heavier oil? I can switch it out in a few days if need be. I have never seen a vehicle needing 5-20 before. Also it does apparently require synthetic oils, how often do you folks change it out?

Maybe I am worrying over nothing...according to the manual that came with the truck (they found it) the 4.6 takes 5-20 and the 4.0 takes 5-30. The factory manual does not differ from either engine so who knows? My guess it makes no difference and 5-30 is fine. Unless anyone else has a thought I will leave it at that...

Does your son's Explorer have the 4.6L or the 4.0L? If the 4.6L, and the owner's manual suggests 5W-20, I'd suggest you drain the 5W-30 and replace it with 5W-20, per the manual. Sure, that may seem like a waste of $30 or so, but that's cheap compared to any potential engine damage the thicker oil could cause. Plus, the difference in fuel economy over 4000 miles may make up that amount fairly quickly too.

-Rod

Plus you will get rattling lifters also with the wrong grade oil.I have heard of a Ford doing this,lifter rattle because of the wrong grade oil.

Sorry, should have mentioned that in the opening post...it is a 4.0 with 70,000 miles on it. I know that Valvoline 5-30(non synthetic) and the durablend both meet the Ford spec, but so far I do not see the full synthetic version specs...hard to think that would not be OK but will continue to check. At least according to the manual 5-30 is OK. I am curious, what do you folks run in yours, if you have the 4.0?

5W30 is recommended so there is no problem with the oil you used. I also use Valvoline 5W30 in mine, but I use high mileage.

I know Chrysler and Ford use 5w 20 in some engines,the only ones so far.A gereral rule is use the recomended oil Ford uses saying on the oil cap and on the emissions label sometimes.

I've used 5W30 instead of 5W20 in the two fords we've owned ('99 Taurus Duratec and '05 Mustang GT). The Taurus ran over 100k with no engine problems and the Mustang is over 40k again with no problems.

The two grades of oil are very similar, the 5W20 is just more expensive so that Ford can charge more for factory service.