Have only had my 05 for 3 months and about to go on a 1500 mile trip pulling a 10,000 trialer thrwe the mountains.
When I got the truck I put in 10/30 Retolla as the Ford dealer told me 10/30 was best & to ignore the manule that recommends 15/40 for summer.
Now that have read the various bullentins it seems that 15/40 is better for sustained towing.
I'm consfused as I have always thought the thinner the better.
Only have 2k on the 10/30 so it seems a waste to change out to 15/40.
10/30 or 15/40 for summer towing?

 

You should get that 10w/30 out of there ASAP and replace it with either a 5w/40 synthetic or 15w/40. 10w/30 is only recommended for extremely cold weather....like Arctic kind of cold.

 

Well I am far north of you- BC. Our avg temp is 20 degrees colder than you.
My service mng said that 10/30 work all year but now that I'm going to tow in the summer I guess I'm getting concerned.
What about a partial drain - say 1/2 new 15/40 added in?
Syn is about $125 up here and I'm concerned about oil leaks going into overdrive.
THnks for the 2 cents!

 

My experience with Rotella Synthetic is it sheared really bad. I noticed that at ~ 4k miles the injectors got really noisy and I suspect it was from the low viscosity oil due to the shearing. I switched back to a 15W 40 and can run the oil to 6k miles and the injectors sound great.

BTW the new Rotella 15W 40 with the latest Viscosity Indexers seem to be holding viscosity really well which includes the new T6 synthetic so this shearing maybe a thing of the past.

Last year during the winter I switched back to a synthetic oil due to injector stiction, which it fixed, but my engine started to leak like a sift. I got the latest flash with the inductive heat to address the stiction problem and switched back to regular Rotella 15W 40 and after two oil changes the leak has literally disappered to the point now my trany bell housing is bone dry again.

I would stick to the Ford oil chart for selecting your oil viscosity based on temps and if you fall into the 15W 40 range that's what I would recommend.

 

Ford's oil chart recommends 5W40 for -20*F to in excess of 100*F. This is a fine all-around choice for most people.



Gentle Ben -

Go to BITOG site and read up on oil shearing for the 6.0L. It does shear, but most oils shear down to the 30 Wt and then the shearing rate slows. The recommendation is to stay at about a 5k mile oil change interval, even with the synthetic (certainly not over the 7.5k recommended in your manual).

Many folks running 5W40 synthetics with no complaints (that is what I run). It is quite fine for towing as well. I do have a hanging drop of oil on the bell housing, but it does not drip. One thing is for sure, 15W40 would be a big problem with injectors in your cold weather (IMO).

I will quickly add though - if your engine does not seem to like a particular brand of oil, then switch. Lots of choices out there. Just make sure it is at least CI4+ rated.

 

Howdy GB........from B.C. (Langley) also.
Been using 15w-40 (Shell Rotella) from day one in my 07 all year round. I also tow a 15,000 lb 5th wheel. No problems to date, but I change my oil every 5,000 km (3k mi.).
As said above.....my prior powerstroke leaked when I switched to syn.......so its dino all the way these days.

 

I just finished my second cycle of Rotella 5W/40, and got the analysis back. The oil was sheared down more than I would have liked after just 5k miles. I didn't test the first cycle. Blackstone noted it was sheared down and wondered why I had changed from 15W/40 which "was working fine for you". They were not concerned about the shear, but did take the time to note it, so it leaves me wondering.

I do not know if the last fill was the new T-6. The stuff I just filled with is, so I'll see in another 5k.

 

A number of members have 140k + on Rotella 5W40 oil and have acceptable UOA's. Interesting that others don't have quite as good results.

The owners manual does suggest 15W40 for towing, but Ford does not recommend use of 15W40 below 10 degrees F. Use in temperatures below this will result in accelerated wear and eventual stiction problems.

 

I think we can all agree that the OP needs to get that 10W/30 out of there. The lesson is, never believe a service writer who disagrees with Ford.

The 5W/40 is a good 4 season alternative. I am toying with the idea of trying another brand, especially since Shell increased their price, and I am having more trouble finding it too. I do plan to stick with 5W/40 regardless.

 

If a service writer ever tells you to go against the owners manual then have his supervisor put it in writing and sign it. Then you can do what ever he says. Until he puts his up on the table to be crushed then I'm not risking my engine or anything else to anyone. For the majority of users on this site you will see preach to "Follow the recommended Service Schedule" that would include the replacement fluids. Heck most say to service sooner.

 

The T6 formula is suppose to handle shearing better due to improved VI's (Energized Protection) is the marketing claim so I would expect your next OC should hold up better.

On a side note: I've read oil analysis from a few who use 10W 30 with exceptionally good UOA (Don't know if they tow heavy loads) and basically most 40 weight oils shear to a 30 weight after ~ 3k miles anyway.

 

heres what I find the most interesting thing....
If you listen to the engine the injectors star to sound a little off when the oil gets a little old, and a little thin.

 

That's exactly what I do--screw the 5000 mile oil change interval. Most times I find that I get about 3500 miles from an oil change and the injectors start complaining. 4000 is really stretching it, especially with a lot of in town/stop and go driving. If I go a LOT of highway miles in a very short time I can get more, but not often.

 

i've towed 14,000 lbs to florida with rotella 5w40. 176,000 and runs like a dream.

 

I think I was hearing the same thing but mine was from the oil being too thin. With Rotella synthetic I couldnt' stand the sound of the injectors at 4k miles.

With the Rotella 15w 40 the injectors are just as quiet at 6k miles as the day I put new oil in.