Question about Shell Rotella T6 5W-40

[RedfireSVT]

i have been using motorcraft 15w-40 motor oil in my 6.0 but was thinking about switching to the rotella t6. i have read that plenty of people use it but i was wondering if it's ok to use the 5w-40 when ford calls for 15w-40? i talked to a tech and he said he wouldn't do it which makes me a little nervous. so is the 5w-40 ok to use in my 05' 6.0? is the 5w-40 just for colder climates? i live in texas where winter is about over and it gets hot here in the summer so should i still go with the rotella 5w-40? any advice would be appreciated as i need to do an oil change. i am also going to try the AR9100 with this change if that makes any difference. thanks.

[TooMuch03]

I use T6 and I am happy with it. I switched from 15W-40 and the truck starts better in the cold, warms up faster, and idles smoother. The T6 is a synthetic oil, so it will dissipate heat better and doesn't foul up injectors like dino oils do. For those reasons it will extend the life of your turbo and injectors. I don't know why the Tech would tell you not use 5W-40. In most situations, it will perform exactly like 15W-40. The only area where it will be different is in cold weather, when it will out perform the 15W-40.

[Arctic Fox]

Should not be a problem to run the T6 all year round

[HeavyAssault]

IF your tech will not run it show him the Owner's manual where is shows the different weight oils and the temp ranges to run them.

I have run T6 in the past even ran a few changes of the newer formula. I would recommend it following the posts above.

[HICKatvRACER17]

ive heard lots of good about the stuff, i am litterally on my way to go pick some up right now. what would you guys recommend for change intervals?
severe?
normal?
thanx

[ParkCity.PSD]

I use it and am happy with it. Starts more easily and idles smoother and a little quieter right off the bat...

[HeavyAssault]

7400 miles w/o a oil by-pass filter kit....NEVER more than 10k if using a by-pass filter. I did PLENTY of research on BOBISTHEOILGUY forum. Made my head hurt but settled with OEM intervals.

[JohnO]

Another happy T6 user here. On my fourth oil change after going from T5, and it's running great.

[jp45601]

7500 miles between oil changes. Severe duty 5000 miles between oil changes. I change mine at 5000 miles.

[AhrmanHammer]

I've been using T6 for the past 2 years... It's great stuff!