5W-30 vs. 5W-20 - CEG Archives

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Well my 3L build is coming to the end as of this July and hope to have it in by July 31. Now on with the oil! I have a 99 Cougar which was included in that TSB about changing to 5W-20 but since I bought the car almost two years ago I have been running 5W-30 Mobil 1 Fully Synthetic with either a K&N or Motorcraft filter.

Now with the 3L, Iâ�?��?�m using the 3L short block (of course, 02 Sable) with also the 3L heads. I got the heads PnP and split ported by Kinger.

Now what oil weight should I run? And what weight are guy fellow 3L guys running? Thanks for all the help.

Read this: http://bestsyntheticoil.com/dealers/amsoil/5w20-cafe.shtml

the 5w20 change was purely for fuel efficency reasons. Its really a personal preference. With that said, I ran 5w20 in my 00 Lightning and did oil samples on it and everything was awesome internally. In my 3.0L hybrid though I run Mobil Syn 5w30.

Originally posted by RTStabler51:
the 5w20 change was purely for fuel efficency reasons. Its really a personal preference. With that said, I ran 5w20 in my 00 Lightning and did oil samples on it and everything was awesome internally. In my 3.0L hybrid though I run Mobil Syn 5w30.

Beat you to it

Originally posted by fastcougar:
Read this: http://bestsyntheticoil.com/dealers/amsoil/5w20-cafe.shtml

Nice read, thanks.

Originally posted by fastcougar:
Read this: http://bestsyntheticoil.com/dealers/amsoil/5w20-cafe.shtml

That's purely Amsoil marketing, and out of date too. They're now carrying a 5w20 and wow, look at that, it works great.

http://www.amsoil.com/storefront/xlm.aspx

Anyhow, if you're using mobil 1, their 5w20 is on the thick side of a 20 weight and their 5w30 is on the thin side of a 30. So, there's actually pretty little difference between the two.

More info (pull up a chair):

http://members.rennlist.com/oil/Motor%20Oil%20101.htm

the clearances in Ford Duratecs, and modular V8s is not designed for 5w20, they are all designed for 5w30.

5w20 in those engines show a noticable increase in wear, and decrease in overall life on extensive Ford dyno testing.

5w20 is acceptable, but is absolutely only recommended for Ford engines in order to increase CAFE averages. 5w30 is significantly better for the overall health of the Duratec.

I use 10w30 in my 2.5 :S

Originally posted by Rara:
the clearances in Ford Duratecs, and modular V8s is not designed for 5w20, they are all designed for 5w30.

5w20 in those engines show a noticable increase in wear, and decrease in overall life on extensive Ford dyno testing.

5w20 is acceptable, but is absolutely only recommended for Ford engines in order to increase CAFE averages. 5w30 is significantly better for the overall health of the Duratec.

Thank you for getting my back

Originally posted by Rara:
the clearances in Ford Duratecs, and modular V8s is not designed for 5w20, they are all designed for 5w30.

5w20 in those engines show a noticable increase in wear, and decrease in overall life on extensive Ford dyno testing.

5w20 is acceptable, but is absolutely only recommended for Ford engines in order to increase CAFE averages. 5w30 is significantly better for the overall health of the Duratec.

Ah, very cool info! Got a link to that study? I'd like to read that. Was it on the motorcraft oil?

Thank you all for the great info. Im going to stick with the 5W-30.

Originally posted by Rara:
the clearances in Ford Duratecs, and modular V8s is not designed for 5w20, they are all designed for 5w30.

5w20 in those engines show a noticable increase in wear, and decrease in overall life on extensive Ford dyno testing.

5w20 is acceptable, but is absolutely only recommended for Ford engines in order to increase CAFE averages. 5w30 is significantly better for the overall health of the Duratec.

How much of an increase did Ford actually see by going to the 5w20? I'm assuming that increased wear is over a long term? My Lightning was fine with 5w20? Is Ford going to 'tighten' its specs to accomadate the 5w20?

Unfortunately it isn't data I can post or do anything more than allude to, because it was Ford internal testing for proving out the use of the 5w20 oil. As far as I know, all the testing still passed Ford's wear requirements, but that it wasn't as good as the 5w30. Some of you seem to think that 5w20 will instantly blow up your engine or something, it won't it will work fine. The difference you would see, is if you took two identical engines, run them exactly the same for 100,000 miles, and then tear them down, and you will see more significant wear on the engine that has run the 5w20. It will be especially noticable for engines run in hot climates.

The real truth is just that it was done for fuel economy reasons and nothing else. It netted something like an overall 0.5mpg improvement in Ford's CAFE numbers, which meant big bucks for the struggling automaker.

Originally posted by Rara:
Unfortunately it isn't data I can post or do anything more than allude to, because it was Ford internal testing for proving out the use of the 5w20 oil. As far as I know, all the testing still passed Ford's wear requirements, but that it wasn't as good as the 5w30. Some of you seem to think that 5w20 will instantly blow up your engine or something, it won't it will work fine. The difference you would see, is if you took two identical engines, run them exactly the same for 100,000 miles, and then tear them down, and you will see more significant wear on the engine that has run the 5w20. It will be especially noticable for engines run in hot climates.

The real truth is just that it was done for fuel economy reasons and nothing else. It netted something like an overall 0.5mpg improvement in Ford's CAFE numbers, which meant big bucks for the struggling automaker.

Ah, probably that old one discussed at length on bobistheoilguy.com.

The truth is, not only is the difference in wear minimal, but it really depends on which oil we're talking about.

20w oils go up to about 9.1 cSt at 100�?º C. 30w oils start from about 10.0. At those viscosity differences, it's just semantics.

When we throw HTHS viscosity cP at 150�?º C numbers into the mix, this becomes even more the case. 20w oils go up to 3.3, which is above many 30w oils, which will drop below 3.0.

Originally posted by Rara:
Unfortunately it isn't data I can post or do anything more than allude to, because it was Ford internal testing for proving out the use of the 5w20 oil. As far as I know, all the testing still passed Ford's wear requirements, but that it wasn't as good as the 5w30. Some of you seem to think that 5w20 will instantly blow up your engine or something, it won't it will work fine. The difference you would see, is if you took two identical engines, run them exactly the same for 100,000 miles, and then tear them down, and you will see more significant wear on the engine that has run the 5w20. It will be especially noticable for engines run in hot climates.

The real truth is just that it was done for fuel economy reasons and nothing else. It netted something like an overall 0.5mpg improvement in Ford's CAFE numbers, which meant big bucks for the struggling automaker.

I was just curious, I ran the 5w20 in my Lightning and didn't see any change or bad wearing with the oil. Hell, last oil sample it was the 'best' 5.4 they had seen that month. I knew it was only for the CAFE numbers, but figured they would have published them if it noted a change in oil viscosity.