Article: Uncovering the Problems with Extended Oil Drains

ChrisD46

Good article still relevant today ... Most vehicles would benefit from using a good oil filter and synthetic oil taking the severe duty and normal duty OCI and dividing by two as your new OCI .

BigCahuna

If you read thru the UOA's there are alot where Blackstone says even tho you exceeded the average oci, the wear particles are nothing to worry about. Like if you change you oil every 4k miles, and have averaged 4ppm of iron. Then you try a EP oil and leave it in for 12k miles. If when tested your iron shows 12 ppm of iron, is that considered excessive wear do to the higher number?.,,,

Imp4

Hmmm. 15,000 and 30,000 mile OCI's. 11 gallon oil sumps. Fuel economy graph that tops out at 8 MPG. 18 year old article was current when API SJ was in effect. Seems to be focused on OTR truckers rather than current day PCMO applications.

Imp4

Originally Posted by BigCahuna
If you read thru the UOA's there are alot where Blackstone says even tho you exceeded the average oci, the wear particles are nothing to worry about. Like if you change you oil every 4k miles, and have averaged 4ppm of iron. Then you try a EP oil and leave it in for 12k miles. If when tested your iron shows 12 ppm of iron, is that considered excessive wear do to the higher number?.,,,
When analyzed from a PPM/mileage perspective, then the answer is 'No' it is not considered excessive wear. You're basically at 1 PPM/1000 miles in both circumstances. Blackstone also provides the average wear rates for your engine as tracked in their database. Note that the mileage in their average numbers may not match your mileage, but they usually state that in their write up. You can then do the math between the average rates they provide and the results from your UOA and compare PPM/miles.

bullwinkle

Originally Posted by Imp4
Hmmm. 15,000 and 30,000 mile OCI's. 11 gallon oil sumps. Fuel economy graph that tops out at 8 MPG. 18 year old article was current when API SJ was in effect. Seems to be focused on OTR truckers rather than current day PCMO applications.
I would add that soot is generally not a PCMO issue (although some gas DI/GDI engines have some), but, as every good BITOGer knows, it's dangerous to extend willy-nilly without UOA.

javacontour

Well, for a good number of BITOG participants, just going to the manufacturer's recommended OCI would be considered an extended OCI.

NO2

The article refers mostly to diesel engines, where particulates are of much greater concern. And seriously, what fleet operator would not maintain their \$150K tractors properly? I guy I knew in college NEVER changed or added oil in his new Chevy, drove 95 on the highway and the engine finally died at 80, 15 times the recommended OCI.

Revving2Redline

Originally Posted by NO2
The article refers mostly to diesel engines, where particulates are of much greater concern. And seriously, what fleet operator would not maintain their \$150K tractors properly? I guy I knew in college NEVER changed or added oil in his new Chevy, drove 95 on the highway and the engine finally died at 80, 15 times the recommended OCI.
Just goes to show you what you can't get from a college education... Common sense that is. I'm gonna guess he didn't pay for that truck from his own money. I find people who pay for their own things usually take better care of them.

dnewton3

Staff member
Interesting article, but not without opportunities for conversation or even outright disagreement. Just my first example: "With normal engine wear rates, used oil metals increase linearly with an increase in miles. In doubling the normal oil drain from 16,000 to 32,000 miles, the used oil metals increase as shown in Figure 3. Abnormal wear results in a rapid increase above the linear line indicating a problem." That's not always true. Wear rates decline with OCI duration, up to some certain point. The metals increase isn't always linear. They completely ignore the topic of normal variation (a topic I wrote about; published in the same journal many years later). Further, they state it's a "problem" to see an increase of metals; that, too, is an over-stated position. Just because wear ticks up, does not make it a "problem"; it is just a marker to start paying closer attention. Condemnation limits should be set and adhered to; set only after careful consideration and consultation. Just because Fe might uptick slightly, does not mean there's a "problem" ... There are plenty of examples of OTR rigs that run 100k miles or more successfully, using a multi-tier approach to full lube system management (UOAs, PCs, prognostics, etc). Running extended OCIs isn't inherently dangerous IF one knows what data to collent and how to interpret the results. What I would agree to is the fact that blindly running longer OCIs with no ability to understand the data won't end well for your engine. If there's a "problem" here, it's that the article takes a one-size-fits-all approach to the topic of OCI extension.

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