Hi, has anyone had any experience switching the 6.5 Diesels from 15w40 oil to fully synthetic 5w40? http://www.dieselplace.com/forum/smileys/smiley9.gif Have you also compared how the various brands of oils like that compare? (I could swear I also saw someone with fully synthetic 15w40, but cant remember which one)

My 6.5 has 180,000 miles on it right now, and I run in COLD weather (commonly -40 F). Should I expect any special problems? http://www.dieselplace.com/forum/smileys/smiley4.gif I hear they are easier to start though.

I'm using the 5w40 Rotella T Synth right now. It pours easier at low temps, apparently. Not important where I live, BUT you should use it or a likewise lower vis oil during the cold (read: frickin' freeeezin!).


I've also used Royal Purple synthetic 15W40 with good results, in gas engines too (actually put it in the BMW K bike as I had no Mobil 1 on the shelf).

I switched over almost a year ago from 15W40 regular to 5W40 synthetic. It seems to have nearly doubled the cranking speed and the engine runs much quieter when started cold.


My truck will never see the 15w40 oil again as long as I own it.http://www.dieselplace.com/forum/smileys/hihi.gif

I agree. I switched to Rotella Synthetic and the first thing I noticed was the change in crank speed. It will be interesting to see how it does here in NE Ohio during the winter.

Everyone mentions Rotella T, but what about the other big oil makers? I havent been able to find rotella synthetic up here yet despite having walmarts.

This will be my third winter using Rotella 5w-40w here in Montana. It works real well, like everyone said cranks better and oil pressure comes up faster in cool and below zero weather. I now use it year around in everything cars, pumps and lawn mowers.


Talk to the Auto Dept manager at Walmart maybe he can order the oil in for you. When they have had runs on the oil here I simply asked them to order 3 cases for me and 2 weeks later I got a call that my oil was in.Edited by: 16gaSxS

has anybody noticed an increase in oil consumption after switching to 5w40? i already use oil and wonder how much more it would use.


amsoil has a fully synthetic 5w30 diesel oil. schaeffer's synthetic blend 15w40 has some really good cold flow characteristics, comparable to conventional 5w30.

when i had my 6.5td tahoe, i ran mobil1 15w50 in it. worked great and easy to get [got a huge amount of it on sale from walmart for $5.00cdn a liter a while back. now if i can find delvac1/mobil1 truck&suv for that pricehttp://www.dieselplace.com/forum/smileys/smiley19.gif]

when i had my 6.5td tahoe, i ran mobil1 15w50 in it. worked great and easy to get [got a huge amount of it on sale from walmart for $5.00cdn a liter a while back. now if i can find delvac1/mobil1 truck&suv for that pricehttp://www.dieselplace.com/forum/smileys/smiley19.gif]





I don't believe the Mobil 1 is rated for our enignes, if not I wouldn't use it.

I would at least check it out in the 15w40 weight to make sure before I used it.

I just checked the Mobile 1 website, and they it was fine to use 15w50 in a '95 Tahoe 4x4 with 6.5TD. I have a '95 Burb 4X4 with 6.5td, which I assume is close enough. I use Mobile 1 15w50 and it works great.<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><O:P></O:P>


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As a side note, I also use Mobile 1 in my air-cooled VW bus. For years vw purists agued against using synthetics in an air-cooled engine. The fact of the matter is, there couldn't be a better place to use it. My VW engine runs from 250 to 300+ degrees. I think you would have to be crazy to run dino oil at those temps. Funny thing is, now-a-days everybody uses synthetic in their air-cooled vw’s.





P.S. I think it is important to note, that you would never want to run Mobile 1 in a direct injection diesel. For example, I owned a '96 Ford F-250 Powerstroke, and those injectors are hydraulically fired using oil pressure. Nothing but diesel approved oil in that baby, and 14 quarts of it to boot.Edited by: Juancho

Hm, I'm hoping to get a large quantity of 5W40 half synthetic oil at a good price soon. I'll reduce changeing intervals with it from 10kkm to 8kkm --- the 10W40 feels worn off after 10kkm while still ok at 8. While waiting for the 5W40, I extended the last interval to 12500km, but that really isn't a good idea, and I won't do it again.

Thus, I'm looking forward to the 5W40 --- as soon as I get it and find the time to make the change, I'll put it in. I'll let you know if it makes a difference --- maybe I'll get even better mileage with it.

BTW, how often am I supposed to change the transmission oil?


The Mobil 0W40 is very nice stuff, but very expensive and very difficult to get here. I've had it in a '96 TransAm with the 5.7 because it has always been running on it, and it ran great. Maybe that'd be a bit thin for the 6.5.
Edited by: 0lee

Update:

I've got the 5W40 now, and it's much better than 10W40. The engine runs smoother on it and starts much easier when cold :)

How come no one is using 10W-30 for winter? It calls for it in the manual.

good luck finding oil at that wieght that is diesel RATED. Very important to note the type of engines that an oil is rated to be used in.

Lotharius,
I'm interested in knowing if you ever found a dependable source for 5w-40 synthetic. The only CI-4 rated synthetic I've been able to find in Anchorage was Valvoline (blue or something like that) and even then it's rare and $$$.

Mobil 1 15W50 full synthetic, pour point to -45C.

Mobil 1 15W50 full synthetic, pour point to -45C. That's what's in my truck right now, but it doesn't have the rating the manual asks for. I did notice that the manual says it can be substituted if I couldn't find the other, but I just figured they meant on a short term basis. I've always used Mobil 1 in my other vehicles, but was hesitant to keep using it in my truck. This is my first diesel and I'm still trying to sort out all the information. I did go with the Mobil 1 15w 50, because I couldn't find anything else and figured I'd rather have improperly rated oil that can actually pour than something with the right rating that is solid as an icicle in my oil pan.

I do plug my truck in at home, but can't always plug it in when I'm on the road, so synthetic is pretty important (at least in my mind).

So far it hasn't been that cold around here though.

when i had my 6.5TD tahoe, i ran mobil1 15w50 with no problems... i even did my own oil pour test for fun.. i put a few different oil types in my deep freezer for 48 hours and poured them into cups... i had castrol syntec 5w50, mobil1 15w50 & 5w30, supertech [walmart] 15w40 semi synthetc, esso 0w30 semi synthetic, shell rotella 15w40 dino...

this was a few years back so some of them might be out of order, but the order in which they poured quickest was..

1- mobil1 5w30
2- mobil1 15w50
3- esso 0w30 [looked like a tie to me]
3- supertech 15w40 semi [looked like a tie to me]
5- castrol syntec 5w50
6- rotella 15w40 dino

the castrol suprized me, but that was long before i learned about the base3 hydrocrack and base 4 "true" synthetics...

my deep freeze sits right at 0°f

That's what's in my truck right now, but it doesn't have the rating the manual asks for. I did notice that the manual says it can be substituted if I couldn't find the other, but I just figured they meant on a short term basis. I've always used Mobil 1 in my other vehicles, but was hesitant to keep using it in my truck. This is my first diesel and I'm still trying to sort out all the information. I did go with the Mobil 1 15w 50, because I couldn't find anything else and figured I'd rather have improperly rated oil that can actually pour than something with the right rating that is solid as an icicle in my oil pan.

I do plug my truck in at home, but can't always plug it in when I'm on the road, so synthetic is pretty important (at least in my mind).

So far it hasn't been that cold around here though.
I wouldn't run improperly (less) rated oil in a diesel, I would go up a grade till I found one with at least the proper rating myself

I'm looking, but as of my last oil change (approx 1200 miles and one month ago). There was no diesel rated 5w40 available. I've checked about 5 different stores and 12 separate locations and all I can find is 15w40 rotella or delo 400. Both of which work great if you can plug your truck in at night, but aren't acceptable if you have to start up below about 10f w/o the benefit of a block heater. It takes waaaaaaaaay tooooooooo long for oil pressure to build up. Thus I was forced to go with Mobile 1 15w40 which despite it's apparently higher viscosity, does indeed pour at -45c (-49f). The Mobil 1 is CF rated, so it is made for diesel's, just not HVY Duty Diesels (I think that's what it means?????) I don't tow anything so I'm not really working my truck very hard, so it shouldn't hurt until I can find a suitable replacement. Which is why I was asking Lotharius if he was able to find any 5w40 synthetic and where he found it.

All of those are available at the walmart here, even the 5w-40 syn rotella. They even have 5 gal buckets.

I know, I read that on this forum and have looked quite often at two local walmarts, but no luck. I havn't asked if they would order it, but that might be the next step.

Go to the part department at the dealer and ask them what they run. Go find one of the few truck stops or fuel places that deal with the big rigs, I can't remember where the ones were that I used when I was there but I know there are a few around. And the newer oils will have different rating numbers(newer maybe a d or g instead of the c rating), also if it is ok for diesels than it's ok for your diesel not need for a hvy dty diesel rating or statement

FAQ at Mobile 1 site quote:



Gasoline and diesel engine oils are formulated differently, but they do have some cross application. This is particularly useful for fleet operations that have a variety of engines. Being able to use one motor oil helps reduce inventory and eliminate misapplication mistakes. But we do not attempt to compare Mobil Delvac 1 to Mobil 1 with SuperSyn™, since they are primarily formulated for different applications. For consumer use, we suggest that you should be guided by your primary application in deciding which synthetic motor oil to use. And keep in mind that some diesel engine oils now call for CE, CF-4, CG-4, CH-4 or CI-4 – which requires the use of Mobil Delvac 1 or Mobil Delvac® 1300 Super.



Whether you have a gasoline or a diesel engine, the owner's manual is the best place to look to determine what oil you should use – but you need to get two pieces of information:

The viscosity grade, and
The API service category (API SL, SJ, SH/CF, CD, etc.)

the new oils have come out with the 'ci-4 plus' rating. i have seen rotella and delo 400 with the new ratings. i have thought about swithcin to rotella 5w40 but i just wish it wasnt so expenseive.

have thought about swithcin to rotella 5w40 but i just wish it wasnt so expenseive.

from what i hear, that stuff goes for ±$12 usd per gallon... that's a good price i think..?

now if i could find it easially i'd run that, or if i could easially get delvac1 i'd run that over rotella 5w40

The delvac is the cheapest stuff walmart sells here, 'cept for the house brand. Something like 5.60 a gal.

It's better to use decent oil instead of cheap oil. Cheap oil is of poor quality and doesn't pay out in any way. $12/gal for (rotella) 5W40 is very cheap and by no way calls for anything of lesser quality that might be cheaper to buy.

Use a good oil in the 6.5 --- the engine is worth it, and you'll notice the difference. I actually didn't expect as much from the new oil as it does, though it hasn't reached its full effect yet. It will take another couple of oil changes before all the remnants of the previous oil (which wasn't bad either) and the dirt are fully washed out. But the engine is already starting and running much better now.

I've got the new oil in an oildrum that holds 60 liters. Maybe you can get something similar, at a good price because of the large quantity. It costs me less than half compared to the previous oil.

the temps are down to 8 degrees Fahrenheit today and the windchill is about -15 F. makes me really ponder changin to rotella 5w40. i guess it isnt real expensive, bout same price as schaeffers. its not as good of and oil as schaeffers but is a 5w and has been suggested by several here who have had good results. and you can get it at walmart. that is a bonus in itself. im gonna look and find the pour points of these two oils and compare.

Don't want to intrude, being a complete newbie here and not an oil expert, but since I stayed at a Best Western last night... :-)

The Mobil web site lists the following about their "Mobil-1 Truck and SUV" synthetic oil:

Meets API diesel engine standards: CI-4, CH-4, CG-4, CF-4, CF




Mobil 1 Truck & SUV is a 5W-40 viscosity grade product and is recommended by ExxonMobil where 5W-30, 10W-30 and 15W-40 lubricants are specified. Consult your owner's manual for specific manufacturer recommendations which may be required for warranty protection.
Mobil 1 Truck and SUV is recommended for use in gasoline and diesel powered trucks and SUVs built by Ford, GM, and DaimlerChrysler.
Mobil 1 Truck and SUV further meets the diesel engine requirements of Cummins, Powerstoke, Duramax and Navistar – for bigger, heavier duty truck applications, such as delivery vans and utility fleets.
Mobil 1 Truck and SUV is fully compatible with conventional engine oils.
Sounds pretty definitive to me that it is acceptable.

found some rotella t dino 10w-30 at the rural king i think im gonna buy. cheaper than the synthetic and it follows the manufacturers recommendation.

If you buy it, please let us know what difference it makes.

So, I found wal-mart had the Rotella synthetic 5W-40 and got some. Does everyone using this run it year around? Being here in Northern Nevada, we get wide temp ranges, and I don't wanna have an expen$ive meltdown.http://www.dieselplace.com/forum/images/smilies/Throwup.gif