Manufacterer recommended oil weight

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Apr 28, 2004
I have a 1999 Ford e-150 van with the 4.6l v-8. Ford only recommends 5w-30 oil. I see on this site 10w-30 is more widely recommeded. Should I use 10w-30 in the warm months and 5w-30 in the winter? Does it really matter if I use 10w-30 all year long? Or should I stick with what Ford says? What is the benifit of 5w-30 over 10w-30.
Well, Ford actually recommends 5w20 for your engine now--they have retroactively recommended this grade for all 4.6 V8s all the way back to 1992. If you don't want to switch to 5w20, I think 5w30 year-round should be fine, and I'd certainly use 5w30 in the winter months.
The 5w30 year round should work fine. You might want to give the Motorcraft 5w20 oil a shot though. In my opinion you are getting a better oil (synthetic blend) for pennies more. [Wink]
I think there is a conventional 10w30 you can use year round in your climate. It can be changed every 4000 - 5000 miles. If you use 5w30 year round it should be changed every 3000 - 3500 miles. I noticed Phillips 66 TropArctic 10w30 is really thin so I would use that year round. Joe
Ford's viscosity recommnedations (like Honda's, and recently, DaimlerChrysler's) are driven by the need to deliver the lowest possible CAFE fuel consumption averages to keep the Feds at bay. The 5W-20 oils, regardless of brand, have ALL shown remarkable performance in the UOA section, notably with less shear-back than conventional 5W-30s (mostly Group II, while most if not all 10W-30s are thought to be blends of Group I & Group IIs). That Motorcraft 5W-20, a synthetic blend (Groups II & III), is around $1.80/qt at discount is additional frosting on the cake. There continues to be a reluctance on the part of some to give these 5W-20s their due, but the UOA results just don't support the hearsay negativity.
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