Oil Change Interval for 15W-40

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Apr 2, 2005
SC Coast
How long should I run the 15W-40 for in my 7.3 IDI Deisel? Do I change it every 3K miles or does this oil last longer? Thanks
Depending on what oil you are using, I change at every 7500 miles or six months, whichever comes earlier with my two diesel vehicles, one IDI turbo and other DI normally aspirated. I only use either Delo 400 or Delvac Super which are HDEO designed to run with extended drain intervals.
Yes Delvac 1300 or Super and Delo 400 are equally matched, very good oils and you would be totally safe.
my buddy has a 94 IDI and he was runnin rotella t 15w40 5000 miles and on his first analysis, blackstone said that he went to long and should have went closer to 3500. this might be different with delo or something else though and your truck might be better in shape than his.
i used the mobil 1300 (i think this is called Delvac) diesel oil- Should it be ok for 5K intervals??
It depends on the oil you use. Some of the cheaper oils will be about shot after 3,000 miles. Some of the better synthetics have been known to be still suitable for continued use after 25,000 or more miles.
It depends on the oil and the usage. Highway driving is way different from town driving. I have analisis of highway driving with 20,000 km that Delo is fine.
widman, How would you rate extreme hot weather performance of Delo 400 versus Delvac Super or MX?
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