As some of you know i've been having mileage issues after some mods I did in Jan, today I think I broke the curse! I figure it would have somthing to do with either the Airdog or van turbo I put in but from my results lastnight and today I think I got it figured out....OIL!

The years prior to me going to Iraq in Jan 09 I always bought the Rotella T Synthetic 5w-30? motor oil in the dark shiny blue jugs. When I got back from Iraq all wally-world had was Rotella Triple Protection(white jugs) and this new Rotella T6 Full Synthetic(new blue jugs). Figureing the T6 would be better than the old sythetic I bought years prior I bought that and did an oil change.

After the 2k mile drive down to TX and getting horrible mileage I figured it had to be somthing simple as a bad turbo or clogged fuel filter or somthing of that nature. To no avail I tried it all but noting helped, the only thing I could think of that I changed prior to the maintenance in Jan was the new T6 oil.

I remember from past oil changs at 3,500 miles(regularly) the Rotella T Synthetic would still have some of its color, hardly black or sooty looking.

Last night I did an oil change(2,473miles on the T6 oil) to the Rotella Triple Protection dino oil(all wally-world had) and the T6 oil was blacker than the night! I could even tell that when I rubbed the dirty oil on my fingers it almost felt gritty like it had lost all of it lubrication properties!!!

I threw in the Triple protection and topped it off and went for a drive, it has the usual change in idle, rpms drop and go back up just enough to notice.

Went and fueled up, when I fuel up I ALWAYS put it to the top of the filler neck right before the cap. Before the problem I've been having I could go 160-180miles before the gauge would move off of F, when I was having the problem it would alway be between 48-52 miles before it moved off of F. Now with the dino oil I got 140miles before it moved!

So now im curious as to why the T6 would cause that issue...its thinner which would mean its easier to move(wouldnt it????) and why was the oil 1000 miles under normal oil change but be twice as dirty??? Maybe I got a bad batch?

I drove 150miles today on top of the 140miles yesterday and i've still got half a tank of fuel left. Mind you I've been driving this thing like grandpa trying to get mileage out it, the tach was always just below 2k rpm and speedo read 63-64mph.

In closing I hope other users of the T6 never experience the same issue i had....next oil change im going to try the T5 blend, does anyone know if the T5 is closer to the old blue Rotella T syn?

Over...

 

I haven't noticed any mpg differences in the use of Rotella Syn vs the Dino oil. I have noticed my oil seems to darken quicker than before, but I attibuted it to a fueling problem. I do, however, have an interest in the new T5 synthetic blend. It meets the same specs as the other oils and pricing seems good, in comparison, also. I would like to try the T5 and see an OA on it to see how it stacks up in longevity. Just my 2 cents.

 

Sounds like a VERY good reason for an oil analysis program on your truck. If you have any uncontaminated oil leftover from the oil change, I would send it in ASAP. There might be something wrong elsewhere.
By uncontaminated I mean after it left your truck's oil pan.

 

subcribed....hope you got this fuel mileage problem figured out.

 

my .02...and just my opinion, i second getting the analysis done, it seems to me there is more going on causing the lower fuel economy than the oil...

 

From everything I've read, the new T5 and T6 oils are exactly the same as before, but just relabelled under a newer packaging/marketing concept. There are supposed to have been no changes made, but I don't have any hard numbers to know that for sure. There is always a possibility that the newer oil might have some slight differences in the additive package which can certainly affect its ability to protect against oxidation (the main reason why diesel oil gets black).

 

I ran another tank of fuel in it and im at 299miles for the first half tank, and 289 miles on the second half tank. 16.8mpg on roughly 35gal, im back up there where I want to be but im still gonna try the T5 blend next time, for some reason my truck hated the T6.

I didnt have a kit to send in for the oil, actually I didnt even think of it when I changed it. (smacks head)

The oil looks like I put it in there yesterday and smells good so im not sure if the T6 I put in there cleaned the engine and thats why it was so dark or what but....as of right now the difference is noticable to my wallet...two fold!

 

It's very likely that the additive package in the T6 did some cleaning out for you. That being said, it is not uncommon to see a truck need 2-3 OCI's when switching to a good synthetic to have it establish all the benefits of the syn.

I know that when I switched over to the Schaeffer 5w40 full syn, it was recommended by Schaeffer that I not even increase OCI's until the second and third changes, but I had already run a high-detergent Amsoil syn prior to switching and was able to jump right up to 13K between changes from the get-go and haven't looked back. Schaeffer had even told me to expect to see wear metals INCREASE in my inital OCI sampling after the first run, but like I said, I guess the detergency of the Amsoil had already "purged" my engine and my wear metals didn't take a surge at all, even with higher miles between changes.

 

Good info guys.