im approaching 10,000 miles on my 07 5.9 ctd and am wondering if its ok to switch to synthetic oil. i've heard 10 k is ok and also heard to wait until 30k. any thoughts and what are you basing them on? thx,,,,,,,
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their take is that syn lubes are economical for the drivetrain
but conventional oil changed frequently is better for their engines
which is laid out on pages 12-13
While the efficiency of drivetrain components is largely fixed by design, gross efficiency
losses can be minimized through proper selection of lubricants.
Synthetic base lubricants are manufactured in the laboratory to exhibit superior high
temperature stability and low temperature fluidity. Since these fluids are created to exhibit
less thickening at low temperatures, pumping losses are reduced and substantial reductions
in spin losses can be realized at low operating temperatures.
Test results indicate no significant difference in engine efficiency between synthetic and
mineral base lube oils at normal operating temperatures. Since the synthetics are more
expensive and, in an engine crankcase, are subject to the same contaminants as mineralbased
oils, they may not be cost effective.
All oils thicken at low temperature, causing increased fuel consumption. The synthetic oil is
less affected by temperature. This makes synthetic oils more fuel efficient at lower ambient
temperatures.
this is the exact same termonology the quick lube joints use that sold america on the 3000 mile drain interval. Now I dont doubt Cummins and their research, however it never stated anything about the addative packages included in the oils, nor the filtration of the filters. With the way these 3rd gen 600+ engines run, the oil gets sooty VERY quick due to the injection process. many synthetic manufacturers have taken this into account and reformulated the addatives in the oil to help with the extra soot that is now introduced tothe oil during normal operation.
another thing about that PDF is it is for the line haul engines, 11 liter and larger. the injectors are generaly fired off a lobe from the cam at that size. due to the difference in the injection process you only have one pulce of fuel where as we have 2 on the early 3rd G tripple nickle's, 3 for the 600 series, and the 6.7's have 5. while this does make the engine quieter, it also produces more power for our smaller engine. all this stuff is for one reason, EPA mandates.
__________________
4/28/07 392hp 716tq on the stock clutch
10/20/07 425hp 798 still on the stock clutch
BIG THANKS to David and the guy's at James O'neal Dodge.
YOU GUY'S ROC
They don't like long drain intervals because if something does go wrong (you spin a bearing, water leaking into oilor some other internal engine damage), you'll drive longer on bad oil and go longer periods of time before you discover it. At least that is their opinion. I won't use anything other than synthetic and just check the oil often at regular intervals.
I was putting 4k to 5k a month on my truck when I first got it and the last thing I was going to do was change the oilevery 3k. That would have been about every 3 weeks or so.
time for synthetic?
