Someone who knows way more about vehicle maintenance than I do suggested that I use a thicker oil in my 5.4, now that is considered high milage and we're fast approaching our hot Mississippi summer months (07 model with 146k, currently using 5w20 -> potentially swithcing to 10w30). Would you agree or disagree that this would be beneficial? I'm leaning towards staying with the 5w20, but if I would benefit using the 10w30 I'd like to understand a little more as to how I would benefit from it (other than saving a little money on the oil).

 

The 10w30 will actually offer less start up protection than the 5w20. There's no reason to up viscosity because of mileage unless you're trying to bandaid a problem. This isn't the 70's anymore. The 5w20 will hold up just fine.

 

I just did my first oil change lol...Quaker State 5w30 I didn't see any 5w20 is that a rare(er) oil? Is the 5w30 fine to run?

 

Maybe in Florida people may think the 5w20 is "too thin" which isn't true, but the old school thinking may make it harder to find there. It should be fairly common though. FWIW I'm running a 5w30 in my 3 valve for numerous reasons (phaser health primarily), but I've also got an oil pressure gauge and do used oil analysis.

 

5w-30 is the safest oil to run IMHO. It offers better wear protection, and still has great cold flow characteristics. But don't use any oil filter besides the motor craft oil filter with a built in check valve.
here's some good info about this exact question
https://www.f150forum.com/f4/5w-30-o...d-idea-130457/

 

Another option: If you live in the upper north part of the U.S. Look into 0W-30 oil... Of course it will more expensive for the fact all 0W-30 are classified as so called {Full Synthetic}... But with this viscosity you will have all bases covered. Just other option... Just a note... We brought the truck home with 5W-20 in the crankcase... The 5.4L really was somewhat full of noise... After the son and I did a minor tune up job... replaced all filters and plugs and oil with Mobil Super HM 5W-30 & 16oz of Schaeffers #132 Moly Treatment... The 5.4L had a drastic improvement in sound... Even the Daughter and Mother noticed the difference... After 1200 miles the 5.4L still sounds smooth and quiet compared to the day day we brought it home...

To be honest I feel I can say... The 5.4L now has better throttle response and no sluggishness what so ever... Which was a complaint of a few owners who switched to a thicker oil... Maybe the New Filters and Plugs + Fresh Premium Gold Coolant had alot to do with this? Maybe it was the hours of cleaning the engine bay and detailing... The 5.4L looks like it just come off the show room floor... I really hope the MPG goes up by 1pt... If so I will be thrilled...

 

I would go to 5w30 oil and a quality synthetic at that.
Would not go heavier than that

 

I would stay with 5w 20 unless the clearance between your oil pump gears is more than normal, otherwise it is best to stay with the 5w20 so all you parts are not trying harder to move thicker oil.

 

sut: pardon my ignorance on This Matter. But how are you going to tell if you have clearance issues between your oil pump gears? Lower oil Pressure? If so? Do we all need to install aftermarket Oil Pressure Gauges?

Just Curious?

Evidently My son's 08 does not have any issues with this matter.... His 5.4L really seems like it likes the 5W-30... Hearing and Feeling really makes a believer out of us...

 

Both are the same cold and the viscosity at operating temp the oil pump doesn't know the difference since it is still better than cold. Clearances don't matter much as the oil molecules themselves are the relatively the same size between a Group I,II, and III.