I hope someone here can give me some insight as to the oil for my 2003 Expedition with a 4.6 engine. I use 5w30 Mobil1 syn. in my 99 F150 with the 4.6 in it but the 2003 Expedition I just bought with a 4.6 in it calls for 5W20. Mobil1 does not have a 5W20 weight oil but has 0W20 synthetic. My question is, is it safe to use 0W20 from Mobil1 and am I running the risk of voiding my warranty if I do use it? Any help would be appreciated.
Thanks,
Mike

 

It's safe to use either of the 2 mobil 1's you mention.

You can stick with the 5w30 or run the 0w20 or the 0w30.

By using Mobil 1 your already using one of the best oils out there.

the 5w20 weights were mostly developed for fuel economy. Running Mobil 1 will already give you better fuel economy when comparing to a conventional.

If it were me, I would choose the better protection of the Xw30 as opposed to the Xw20. But like I said either one will work great.

 

Either the M1 0w20 or 5w30 will work just fine.

No warranty issues with the 0w20 - it exceeds the requirements of Fords 5w20 spec.

Warrnaty is not likely an issue with the 5w30, but technically is not the correct lubricant required by Ford for warranty issues. That being said, 99% of dealers out there have no clue.

Also there are no internal differences to require the use of the 5w20 between the 99 and 03. In fact, Ford even back recommends 5w20 to your 99 model.

If it were me, and I needed to keep one oil on the shelf, I'd pick the M1 5w30 for simplicity sake - more readily availible and priced lower than the 0w20. Nothing wrong with the 0w20 though.

 

Is using 15W-50 Mobile 1 in the 5.4L ok, or would it be a problem??? Truck is past warranty, has 67,000 miles.

 

First of all it does not. It the dealer tells you that, get his name and the dealers name, you can send it to FCC and they will send the dealership a little note that you can NOT tell customers that it will VOID the WARRANTY, that is againce the LAW. If that was true, why is there so many oil companys?

 

Why not just use Motorcraft(Conoco) 5W-20?

 

The problem with an oil that thick is that it does not flow as well as a 30w and some areas will lack sufficient flow of new cool oil. 15w-50 is for race engines that run hot and the oil thins out to a 30w, or engines build with larger clearances.

Your engine was designed around the flow rate of a 20-30w oil. Using 50w will not ruen the engine, but just don't think thicker is better.

 

With the 15w-50, you'll get noticably lower gas mileage too.

 

Mobils 0W20 is rated to meet the 5W20 Ford Spec. It is stated right on the bottle as well as meeting a spec for Honda's. Wallyworld typically always has it in stock for the low price of $4.79 a bottle. Or you can move further down the aisle and pick up the Motorcraft 5W20 for $1.27 and change every 3K and still have great protection.