Question about oil changes

[Newdieselfan]

As posted yesterday evening, I just bought a 2004 King Ranch with 235,000 miles on it. I took it to WalMart yesterday for an oil change and put in 5W-40 Shell Rotella T. Is this a good oil for future use or do you recommend something else? Cost $118.00. That was a shock despite having been told that everything costs more for diesel trucks.

Newdieselfan.....

[peobryant]

I go to my local John Deere and get 15W-40.

[Austin G]

I am using 15w-40. Rotella.

[GoFastPadre]

Originally Posted by Newdieselfan

As posted yesterday evening, I just bought a 2004 King Ranch with 235,000 miles on it. I took it to WalMart yesterday for an oil change and put in 5W-40 Shell Rotella T. Is this a good oil for future use or do you recommend something else? Cost $118.00. That was a shock despite having been told that everything costs more for diesel trucks.

Newdieselfan.....

You should be using 15W-40. I know you just had it done but I would not leave the 5W-40 in it for long, especially with 235K on it.

[shu873]

I'm going to disagree with the majority so far. 6.0's LOVE synthetic oil, and there is nothing wrong with the 5w-40 grade. There is a pretty significant difference in the injectors between the 6.0 and the slightly older 7.3's. The syn oil will flow better in cold conditions and can help prolong injector life. The trick is just because you run syn oil, don't fall in to the trap that you can go with extended change intervals. 6.0's shear oil like it's their job. I run the rotella syn 5w-40 too with a motorcraft filter it runs about $100 tax included to change it myself. I change the oil/filter at least every 5k miles.

[Hank]

Originally Posted by shu873

don't fall in to the trap that you can go with extended change intervals. 6.0's shear oil like it's their job.

Sorry for the hi-jack.......

Where is this documented? I have been trying to learn more about 6.0s and oil shearing. Is there a report somewhere that I can obtain? Thanks!

Edit: I'll check back later. Guess I missed you? Later..................

[kinghawg98]

I used 5w40 this oil change and seem to have harder starting. It takes longer to crank and has a harder time idling off the bat. When it is warm, it runs well, but cold- 60 deg and less I am experiencing that hard cold start problem. any ideas?

I put this here not as a hijack, but hopefully others will see and share experiences- maybe someone else had the same problem, maybe its just me.

[RYAN SHAE]

Kinghawg98 that doesn't sound like an oil problem. A lighter weight oil ie. 5w40 vs 15w40 should help the cold start problems not make them worse. If I had to guess then I would guess that it is your FICM going out and not the oil. Now this is just a guess. Have you pulled any codes? That would be the first place I would start, but that is the way mine was acting when my FICM went out. When it goes you are stuck so don't "wait and see" or you will be "left in the cold".

[shu873]

Originally Posted by Hank

Sorry for the hi-jack.......

Where is this documented? I have been trying to learn more about 6.0s and oil shearing. Is there a report somewhere that I can obtain? Thanks!

Edit: I'll check back later. Guess I missed you? Later..................

There's a few old threads on here discussing it in more detail. Not sure what they were titled or if that was even the main topic of the threads. A lot of the information I have found has been on other boards as well, and it's not all documented in any way. Just words of wisdom from techs/mechanics that are a lot smarter than me...

[maddogv21]

So would running 5w-30 Amsoil in my 7.3 be a bad thing with a cold winter approaching? I changed my oil about 3-4 thousand ago and seen no problems. I get much better fuel mileage, about 2 miles more per gallon.....I know I was surprised too.