I normally like to do my own oil but because the dealership screwed up last time I had a free oil change today. Took it in and waited an hour and a half for them to do the work. Got my receipt and was walking out when I noticed that they had used 5W-20 on my '98 4.6l. Took it to the manager and told him to change it, and since there was probably a quart in the filter, change it too. This time I was very clear that I wanted 5W-30 and gave them back the keys. 40 minutes later I get my truck back and the new receipt...and they had done it again!! 5W-20. I told the manager again and he said they would fix it, but after explaining that I didn't want his incompetent people working on my truck anymore, I just left.

So here I am with 5W-20 in my engine. I personally think that it's too thin, but If I can get away with it I'll just leave it till the next change. I just wanted to get everyones opinion on whether you would change it or leave it.

 

I would leave it and see if the gas mileage would in prove with it in.

 

I should have been more specific in my first question. What I meant to ask is if there were any interior changes to the 4.6 in 2001, that are different than the '98, in preparation for the thinner oil. Different Rings? Different main bearings? Different valve guides? Different oil pump? Etc... What I really want to know is...will the thinner oil in the '98 engine hurt anything?

 

Advantages to lighter oil are..Less dry starts, better fuel economy, better flowage at cooler temps...with winter here I would change to a lighter oil anyway...I'd leave it...I'd consider running lighter oil in the winter anyway IMHO...

 

Unless you are going to be running in very hot weather, not likely at this time of the year, you will do no harm by running lighter oil. Even in hot weather the only thing you might see, is slightly increased oil consumption, but frankly these engines are so tight, even that would surprise me. I would just leave it, and change back to 5-30 next time.

 

I have a 1997 4.6 auto and I was told the newer engines are built tighter and a older engine may leak because of being not a tight as a newer engine. This came up when I was putting in o-w 30 mobil 1 in the truck. In the final thoughts of the discussion they said atleast put in the 5w30 in the summer and the 0w 30 in the winter.

If it were me I would have had them put in the 5w30 for the 2nd time and tried to get a transmission flush for free also.

 

I don't think anyone (at least around here) has documented any changes in tolerances beween engines that were originally spec'd for 5w30 and engines spec'd for 5w20.

5w-20 should be just fine. I'd be curious if you note any fuel mileage changes with the lighter weight oil since that is one of the supposed benefits of the oil.

 

Minor changes in engine, Ford switched to improve their CAFE rating. 5W-20 will be fine just keep it til next change.

 

In 1971 I worked for a mechanic/engineer in an auto repair shop. He ran straight 20w20 in his truck all year around, and it gets damn hot in Albuquerque in the summer. The truck was a 1955 Chevy (sorry) and was the first vehicle that I ever saw go over 200,000 miles on the original engine..........we did a valve job on it at about 220,000 miles..........

I feel very secure using 5w20 in my new Supercrew....not a bit worried...........

 

Ford has approved the use of 5W-20 in older engines. I think all the way back to engines built in the early 90s or late 80s.

 

There is a TSB about using 5W-20 in older vehicles. Read it here.
https://www.f150online.com/forums/sh...ghlight=amsoil

Scroll down to the post by Y2kXLTSport.

 

Thanks for the info. It was exactly what I was looking for.

Gopher...you're in luck, I actually keep track of my fuel economy. The thinner oil shows no benefit in gas mileage. I gained .1 mpg from my usual calculation, but considering how minute the gain is, I would say that it falls into less than one standard deviation. Totally insignificant to me. I'm switching back to 5w-30 next time.

 

Well, thats about what we've all figured it woul be. Doesn't mean much to you and me, means a whole lot more over a fleet of many hundreds of thousands of vehicles you are trying to meet CAFE requirements with.

Good Luck!

 

How's that 5W-20 look? Can you even see it on the dipstick?

 

Dennis, it's funny that you mention that. After I gave the oil some time to drain back down and went out to check the level I was really surprised to see how clear it looked. Maybe it's just placebo but I really don't trust this stuff, at least not for longevity.