So yesterday I changed the oil in my truck, before I changed it, my delta's around town were always within 4-5*. I left for work this morning and noticed that my EOT and ECT delta's spread to 8-10* around town, but once on the interstate they stayed within the 10-12* range like normal. Once I got back off the interstate, they went back to the same as before i got on. I have no idea what oil was in it before, it's whatever the dealer had put in it (didn't buy from a Ford dealer), but I put the Rotella15-40 back in, with a Motorcraft oil filter of course. I know this doesn't make sense to me, so I was wondering if someone could shed a little light on that for me as to why just changing the oil made that difference. I watch my delta's religiously,so that is something that hasn't been normal.

Thanks, Scott

 

Make sure you have the OEM oil filter cap as that will allow the oil to bypass the oil cooler.

 

Bought a brand new one yesterday.

 

Most of us here us Rotella T 5w-50 Synthetic. My Delta's Stay within 3-4 in town and 5-6 on highway. 8 degrees when towing. From time to time if I play ahead I will use Amsoil 5w-50 Heavy duty. All in all its about providing the best protection for you motor

IMO 15w-40 standard white bottle rotella is minimum protection.

 

I thought the majority of us used t6 5w-40

 

I run 10w-30 and my delta's are identical to those mentioned above, I wonder if the dealer or previous owner you bought the truck from knew there was an issue and had something thinner than what you put in to mask the problem.

Or you could have bumped a wire and are getting flawed data, you always can switch the oil and coolant sensors to verify accuracy.

 

Maybe I should drain it out and put in the 5/40 synthetic. Must have been what was in there before, but I had no way of knowing. I know the filter was wrong, so I figured the oil could have been sub standard as well. We run the 15/40 in all our 6.0's at work with a gazillion miles on them and it seems to work really well. Oh well, here's to spending another 100 bux to change my oil again.

 

Fat fingers that's all I got to say! Thanks KIDkiser

 

Honestly, as long as the temps don't go any higher I would get as much life out of that oil as you can then change it. Just a suggestion to save you a couple of bucks.

 

I really can't see where a different oil brand or weight would change the deltas.

 

I seriously doubt the oil weight and type would change the delta that much, but it sure will be interesting to see what you find. Can you read data somehow, would be interesting to know what your cold soak, is on oil temp, coolant temp, trans temp, as perhaps you have a sensor going off or a wire loose ect? I think the delta is very much to do with where the coolant temp is and what flow from the water pump you are getting, as the thermostat reducing flow will impede the cooling in the oil cooler somewhat. I have noticed cooling of the oil doesn't really occur until coolant is over 190, until then, the oil temp seems to run a bit high during warm up. Then if outside temps are colder, my oil runs higher, ie long down hills in cold weather, the oil status up longer..... Just my observations, I have been observing for 8 years on my outlook monitor.

 

The oil isn't the cause of the delta change and your not checking the deltas correctly to start with. I don't see any looming problems with what you posted. As stated before, use the oil that's in it and then put what you want at the next oil change. Many use the 15w40 with no problems at all. Make sure to use OEM filter and cap.

 

Just wanted to clarify, I may have misspoke. Better oil reduces friction with should lower oil temps. Slightly. However the differential in temps can be caused by several factors

EOT or ECT temp sensor
Wiring issue
Oil Cooler partially obstructed

Bottom line monitoring the temps is the best thing you can do.

 

The highest that my oil temp has ever seen was exactly 200*. That was sitting at a bank drive through for about a half hour in 85* ambient temps. Otherwise, it has never gotten over 196* while driving, and the ECT never over 192*. I have looked under the hood, and do not see any wires that I would've even remotely come in contact with. I did buy a brand new oil filter cap from the Ford dealer in a Motorcraft bag, so i definitely have the right cap. Just seems strange to me that my delta's have been a mirror image from day to day since I hooked the scangauge up. (Six weeks) I change the oil and then they become different for some reason. I originally had the thought that the thicker oil is retaining the heat a little longer than the thinner stuff that was in it before and is just taking a little longer than before for the two temps to come into the acceptable range. I'm getting ready to make a trip at the end of this month to Gilbert La from here just south of Richmond VA. The trip while be 1020 miles one way, but I will not be pulling anything. Just one race bike that weighs about 220lbs in the back of the truck and maybe 100lbs worth of other gear. Just want my truck to be healthy for the trip.

 

Check your cold soak temps now, and did you happen to see them earlier? I am thinking it's more than likely the change. I would get your time and miles out of the oil that's in it, don't worry about changeling until it's due. Then decide what oil to switch to.