(H8GAS) this might work for you.every 3000 miles change filter an add one quart until you get 15000 send a oil sample away to see what they say,or change all the oil and start all over again. use high end filters if you try that system.

 

they are talking about the HDD 5W-30, it's a heavy duty -30 for diesel. It's got a higher TBN than the Amsoil 5W-40 but is virtually the same as the Amsoil 15W-40


https://www.amsoil.com/storefront/hdd.aspx?zo=1478251

 

Why if the engine builder calls for 40 wt ,for the 25 years diesels have been around ,why would you put 30 wt oil in it ?? a $6000 option ...??

 

(BELGIANMAJIC) great question.i think its human nature to try to improve what you have even if it doesnt need it. this is really true when it comes to CTD owners. i dont think this 5-30 oil would be a issue but amsoil had to go and say that it was there best diesel oil ,and most people want the best .

 

WELL ,MY OPINION IS: If their "BEST diesel oil is a 30 wt ....they better keep trying

 

I have run both weight oils and I like 15-40 more then the 5-30....5-30 did not make enough difference... other then a lighter wallet

 

(BELGIANMAJIC) im not saying it is, they say it is. my truck is a 06 with 6500 miles an i am looking forward to changing to syn. oil .i do a lot of towing and i am still not sure wich weight oil i am going to use .i have two other diesel trucks that have 15-40 in them.but for some reason that i cant figure out myself,im leaning toward the 5-30 i think its besause they make an sell both oils so why would they say one was better than the other unless it was.its going to take someone smarter than me to figure this one out, i have talked to several tecks at amsoil about the heat while towing an they say the lighter hdd5-30 oil does better besause of the additive package they put in it..,I DONT UNDERSTAND WHY THEY WONT SAY IN WRITING THAT THE HDD15-40 IS 100%SYN.THEY WILL TELL YOU ON THE PHONE THAT IT IS BUT THEY HAVE NOTHING INPRINT TO BACK THAT UP ON THE OTHER HAND THE HDD5-30 DOES SAY 100 SYN. maybe its different base stock but they say not again this is not in print there is a lot of price difference in class 3-4-an 5 base stock oils. the hdd5-30 has a much higher price than hdd15-40 that makes me think the hdd5-30 is using a higher base stock an they might not want you to know that.an i still dont know wich one im going to use.

 

For those who want a 40 weight, 100% synthetic oil you can use the Amsoil 5w40 but they do say if you want extended drain intervals you need to do UOA's. And for those who worry about a lot of contaminants in the oil then hook up a by pass filter system to your engine and IIRC it will filter down to 2 micron but also do UOA's to be safe.

IMHO I think the reason they have always said to use 15w40 oil except in the wintertime is that dino oil was all they used 30 years ago. I also think we can agree that Dino oil does not hold up as well as synthetic oil does.

IMHO with the Amsoil 5w30 oil in my engine has less noise then it did with the Rotella synthetic 5w40 oil I took out of it, so they must add something good to it if my engine runs quite at all speeds, even idling.

 

Jones, at what mileage did you switch? Do much towing in those miles? Trying to gauge when I should switch over... My tdi loves the amsoil, quieter and a few more mpg's on ave, but I still OC every 5 K since it's cheap insurance and I have a lift.

 

Amsoil 5W-30 severe diesel oil has an additive package that enables the oil to go for extended drain periods in a working diesel engine. Those additives also give the oil a greater shear strength over a 15W-40 engine oil. The viscosity extenders thin down better to provide a lower pour point in cold weather and thicken up when the engine is hot in the summer and needs more viscosity in the lubrication. I used 0W-30 ESSO 100% synthetic engine oil and started a dead cold gasoline engne in the winter at -30F, and the same oil protected the engine in the summer heat in Louisiana. I now have 5W-30 severe diesel Amsoil in that gasoline engine and it performs better than the 0W-30 100% synthetic in the winter and better than ESSO's 0W-40 100% synthetic in the summer. The viscosity extenders in Amsoil are superior to the extender in other synthetic oils. Amsoil also uses better synthetic base stocks. The ESSO synthetics were changed once a year in the fall in our gasoline engines with over 20k kms between drains. Amsoil is doing the same or longer drain periods and the engines run perfect and give good gasoline mileage.

Cummins always recommends 15W-40 because they want to protect their engines when operators put conventional oil in the crankcase. With conventional oil in the crankcase the starting motor can hardly turn an engine over when it has been out over night in -30F to -40F temperatures in a wind without being plugged in. A big oil company will leave their diesel units running 24 hours a day in the cold winter. I have all Amsoil lube oils in my Dodge and will use nothing but 5W-30 Amsoil in my CTD after the break-in period.

 

What is the best way to get the sample without contaminating it? It seems like you could clean around the drain plug and then crack it loose a little but the potential for other crud getting in the sample is there, right?

 

Now im wondering does it matter WHEN you change over to synthetic? I mean is there a time when it has TOO many miles to do any good? Also I have heard that switching to synthetic can cause leaks any truth to this?

I haul all the time and wouldnt mind better oil and for that matter extended oil changes along with a by-pass filter.

 

How many miles to break in before switching to synthetic...10K?

1Coyote

 

I think Cummins recommends 25k but if you tow heavy you can go sooner..
tons of guy's have

 

At 10K I used Rotella 5w40 synthetic and at 13K went to Amsoil 5w30 synthetic. IIRC Cummins has now said any time after the first oil change as per several emails posted at other web sites. I know I did my first oil change at 1150 miles so I think it maybe a good idea to wait until it has at least 5K if you have worked the engine hard or longer if it has not.

IMO