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what kind of oil should i use?

168K views 22 replies 16 participants last post by  jayfa82 
#1 ·
so im due for a oil change for the past 2 times i been using synthetic mobil 1 turbo diesel 5W-40 i herd from people that work on big rigs that synthetic oil is not good for diesel motor's reason 1 is cuz its to thin not sure if its completely true i don't see any leaks on my motor. people also say that i should be using 15W-40 not 5W-40? would ROTELLA non synthetic be a good choice? would me changing from Synthetic oil to regular hurt my engine?
 
#5 ·
why is it recommended for duramax engines?
 
#7 ·
I have always run Rotella 15-40 in every piece of diesel equipment I own. Boats, tractors, trucks, mowers, etc. I have done this with great oil analysis and limited leaks on rough service motors tractors/boats. We live in Hatteras and its rough as F^%K here most of the time. Spoke with Rotella yesterday about switching from 15-40 to 5-40 because I had a hairbrained thought about switching from something that is not broken. The tech told me directly that diesels were not designed for synthetics regardless of some of the upsides to them ie better cold start. Aside from the occasional "yeah I use synthetic with no problems," every mechanic that I know and trust said stick with Rotella T 15-40 because it was designed for these engines and handles soot very effectively. They do 100's of O/A on various engines and find that Rotella maintains the highest test results acrosse the board.

The Rotella tech said "try 5-40 if you want, but if you have leaks switch right back to 15-40." Then proceeded to say "why would you switch when you have no leaks/problems and you are gaining very little by switching anyway." End quote. Mind made up 15-40 went in the truck last night...again. The tech knew I was buying Rotella no matter what so he was unbiased except for the $4/Ga. diff in retail price. I asked him if he would run synthetic in my 450 cummins c seris and he said no...absolutely not. Again, direct from Rotella.

Let the wars begin...However oil is personal preference...cant debate that. Choose what oil you feel comfortable with. Engine companies dont make oil and oil compaines dont make engines, so if either fail, the other is not going to pay for it... Rotella isnt buying you an engine if you run synthetic through it and it goes ZING POW. Buy what has worked for billions (with a B) of miles on over the road trucks pulling 80k LBS Rotella T 15w-40.
 
#8 ·
Oh my this is crazy stuff what to go with my nabor had a 2001 cummins all he runs is Rotella 15w-40
 
#9 ·
Is it still running?
 
#10 ·
lol yeah he said that should be the best oil for diesel thats why i been looking into the Rotella hi only has 60,000 miles
 
#11 ·
The mechanics I talked to and use regularly, service trucks with with a million + miles on them and boats with 25,000+ hours. They will only run Rotella and only the 15-40. For what its worth.
 
#12 ·
so if i was to change from synthetic oil to regular it would be OK? it wont heart or damage the motor?
 
#15 ·
no switching from synthetic to standard oil will not hurt your truck. i use mobile 1 15w-40 with 2 quarts of lucas in my duramax and my old 12v. i swapped both of them over from rotella. i have gotten better oil pressures out of the delvac by itself so that sold me on the delvac due to both my engines having over 150,000 so obviously there getting older and better oil pressure is not a bad thing at all. although ran rotella for years in the 12v and never had a problem, and you cant go wrong with a company thats been in the oil buisness for 75 years like rotella has been.
 
#16 ·
Its all preference really. People swear by their favorite brand. Hell, I heard Amsoil helps anything from Erectile Dis-function to Pattern Hair Loss.
 
#18 ·
The best analogy that sums up the difference between dinosaur oil and man-made is at the molecular level. Consider both synthetic and fossil oil molecules as round marbles. Fossil formed molecules are not perfect, meaning they come naturally in varying sizes. Using marbles again as an explanation, some are “boulders” medium size and some are “pee-wee’s,” all are round and very slippery. Synthetic molecules, being man-made, are all exactly the same size, which means no one molecule carries more of the load than the next. This is why “oil shear” is greatly reduced with synthetic. Another analogy would be the difference between an asphalt road verses a cement road, both are smooth but one is more uniform. Heat is also a major cause of oil degradation. Here again synthetic far exceeds fossil in thermal-breakdown.
 
#19 ·
Using synthetic oil in these trucks is useless unless you plan on extended drain intervals... 12k, 15k, 18k mile changes. If you're using Amsoil, T6, Mobil1, Etc and changing every 5k-7500 you are flushing $ down the toilet. Just fact. During short intervals, you gain no advantage using synthetic. I use cheap Mobil Delvac and it does the job perfectly fine. If it didn't, big guys wouldn't be using it in their built motor, 10-11 second trucks.


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#20 ·
Delvac, or Rotella 15w-40. $30 for 2.5gal at Wal-mart.
I was extremely pleased coming from an Audi to this truck. I got sick of $100 oil changes every 4k in a hurry. $40 every 7500 is FINE by me.
 
#21 ·
I use rotella 15-40
 
#22 ·
Where I work we do lab tests on each engine's oil when its serviced...............We use dinosaur oil and change every 8000 because........... and here's the deal............. running synthetic is not going to keep any more or less dirt and grime out of your oil..............True it wont break down as fast as dinosaur oil but both get the same amount of grime..........but because we are a public entity we have to use the most cost effective oil..........Tests show that the synthetic is in better shape at the the end of the cycle at 8000..........Im going with the best oil for my motor for the 8000 mile interval..........
 
#23 ·
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