I bought the case of 5W30 at costco not even realizing The oil cap says 5W20. will there be any issue if i go ahead and use the 30? Can some one refresh my memory on the difference. I live in Phoenix so the next couple months are going to be 110*+ temeratures.

 

I would use it. My 97 5.4 5w-30 is recommended. The only reason Ford changed to 5w-20 is emissions. I wouldn't think twice about using a 30 weight for a while.

 

Ive used it for 2 oil changes already.

 

It has nothing to do with Emissions. It has to do with raising the MPG figures for CAFE and also the cam phasers on the 3 valve.

You should be fine with the 5w30 though. I however prefer to run the 5w20. Ford use to give you a range of oils to use in the owner manual seems that is no longer the case which makes me wonder if something were to happen would they try to blame it on the wrong weight of oil?

 

+1

Also, since you've already been using 5W20, why not just take it back and exchange it or get a refund?? Is your Cosco like 200 miles away or something?? Is it going to hurt anything at all?? No. Would I run it?? No. I'd go back and get the 20. The 20 is not too thin even in your Arizona heat. The centistoke of an oil is determined at 100* (C) oil temp, not outside air temp. Your oil does not run that hot even on 100+ days outside.

 

I have not problem taking it back. I was just curious if it mattered. Oil temps don't rise with outside temps??? I know my tranny temps go up 10-15* over the summers here!

 

I would guess that has to do with the cooling capacity of the trans cooler. Higher outside temperature provides less cooling to that little radiator.

 

You have to be a little care full about using a thicker oil. The tolerances on the bearings are probably designed for the lighter oil. It may take it a little longer to get the oil to the bearing surfaces and in the long run you no what that means.
It's also for fuel economy, which is probably negligible.
Try sticking with the oil recommended. I use Amsoil 0w20 full synthetic in my truck all year round.

 

I would just take it back for exchange personally.

 

That's not what I said...re-read it. Oil temps do rise with outside air temp, but not to a critical point...unless you're doing some serious towing in that heat or holding constant very high rpms....the two biggest influences on oil temp.

What I was trying to convey was to the point of the oil "thickness". You eluded to the fact that you didn't mind using a heavier oil due to the hot Arizona temps, but I was trying to tell you that's not a huge factor. The "thickness" of the oil (centistoke) is based on an oil temp of 100*. Your oil temp does not run that hot under normal conditions...even on the hottest Arizona days, thus no real need for a "thicker" (i.e. 30 weight) oil just because it's hotter outside. Does that make sense?? Like jbrew said, just take it back. If you're like me, it would drive me completely bonkers to run a different oil anyways...I wouldn't be able to sleep at nights

 

If the vehicle is under warranty, it is always better to go with the stated spec just so no one can say you didn't abide by the rules if something was to mess up.

Personally, 5w30 should be just fine. My L requires the same 5w20 and that is what I use at ever 5k miles, but I highly doubt anything would mess up if I started using 5w30 instead.

 

DANG...And I thought the "W" word was gonna stay out of this one!!

 

Good post. Take it back and exchange it.

I just changed my oil with 5w20 Mobil 1.

 

I know your feeling, every time I pass the Mobil 1 in Costco @ $29.95 a 6pac vs $46.00 Amazon. But I stay with Motorcraft 5w20 from wallys

 

Yeah i know I keep leaving the comment card telling them to get the 5w20 also.

I do still buy the 5w30 from them as a few of my other vehicle use it.

And as much as I hate to do this I do go to Wally World and buy it in the 5Qt Jugs as it is about one of the only places that carries it around here. So when i go I spend a fortune and stock up on the oil and Motorcraft filters. Other than that i refuse to shop at that freakin place.