99 Ford Expdition 5.4L

[billtx]

Ford recommends 5W20 for this engine starting in 2001. Is it compatible with the 99 model?. If it saves me some gas money it is worth it - my fuel bill is outrageous.

Vehicle has 140k miles, mostly on Mobil 1. Just tried havoline 5W30 as a result of reading about it on this website. Autozone has Motorcraft 5W20 syn blend for a little over $2/qt, wanted to try it.

I'm also just starting the cleaning cycle with Auto-RX. Oil consumption has always been high (qt/2000 miles) and it seems to get dirty quicker than it used to. At best, it gets 12MPG with my wife running around in it.

Thanks for your help.

 

[pitzel]

5W-20 won't help the fuel bill much, but neither will it cause the engine to wear out more quickly.

 

[haley10]

billtx, wife has 99 Lincoln Navigator. I can honestly not see a difference in running Motorcraft 5w-20 or 5w-30. Around 15 mpg is average. About all you can do is to make sure it's in a good state of tune and keep a clean air filter and proper tire pressure. These will affect it more as well as driving style.

 

[Steve S]

has the mpg changed since purchase of the vehicle?

 

[billtx]

MPG has always been poor, probably has to do with my wife's driving habits. I changed the spark plugs and went from 10.x to 11.x MPG. I bought it used with about 22k on it, around a year old.

 

[NewGuy]

My wife has a '98 5.4L Expedition. It burned oil using M1, but I changed the PCV valve and switched back to dino. It hasn't burned oil since.

I ran Havoline 5W20 for 2 OCIs and it ran well. It might have increased the fuel mileage slithly, but I noticed a bigger improvement after the ARx treatments. Gas mileage is still horrible though.

 

[NewGuy]

One more thing...if you change the PCV valve go to the Ford dealership and buy a MC PCV valve. I tried to other brands from part stores and they did not work well at all. The MC part comes with a grommet and is the same as the OEM part. It is about the same price.

 

[darkdan]

you're welcome to review the spreadsheet of modular motor UOA and decide if 5w20 is right for you. Please right click and save as:

http://www.dantheoilman.com/modular.xls

If you want a little bit more gas mileage then get electric fans and underdrive pulleys. Not onl will you get about 14 to 20 more hp....but a decent bump in mileage.

 

[billtx]

Newguy, where is the PCV located? I took a quick look but could not see it. I thought about changing that out also.

 

[billtx]

Thanks guys.

I think I'll give the 5W-20 a try. Sounds like it can't hurt but may be able to help.

Note that I can get higher mileage when I drive it - my wife is a good test case, she never changes her driving habits.

Also would not be a bad idea to try and decarburize things, I've used Techron in it in the past. Not sure how that compares with Seafoam.

 

[MNgopher]

Likely you will notice very little change from running a 5w30 by switching to a 5w20. I know I didn't note any difference over a 1 year period in my '99 F150. My UOA's showed virtually no difference in wear between the oils, so they both work fine.

I did note a 5+% fuel mileage drop using 5w40 over a 1 year period - needless to say that experiment has ended (and wear was not out of statistical noise to call an improvement).

 

[Islandvic]

Get new PCV valve and decarbonize combustion chambers with SEAFOAM DEEPCREEP.

2 apps will do it.

1 qt every 2000 miles is not bad. Its with in spec.

Try Valvoline MaxLife Dino 5-30. WalMart has it for $8.98 for 5qt jug, and you can pick up a MoCraft FL820S filter for $3 at the same time.

It has between around 15%PAO syn.

 

[wander2039]

Huh I noticed a 1.5-2 mpg difference when I switched to 5w-20 from 5w-30 in my 5.4L. It ranges from 16.5 to 17, before it was 14.5-15. It seems to internal dyno I don't need to push it as hard with 20wt. I notice the harder I push the more oil it consumes, such as pulling a heavy trailer and keeping it out overdrive. On 400 mile trip pulling a heavy trailer I got 12-13mpg, their has be something not right with yours. I do have a AF1, dual exhaust (probably hurts more than anything), 45 psi in all tires, so I guess that helps.