My Estimate on OCI

[iExcel]

OK. My Owners Manual suggests that under severe conditions, I should change every 3 months/3000 miles; under normal conditions, every 12 months/7500 miles.

Let's say, in an ideal world, I drive all the 7500 miles on the highway at 60 mph, which should be considered *normal* conditions. Then the engine would run 7500/60 = 125 hrs before it requires an oil change.

So, if I drive 1.5 hr a day, 125 hrs is about 83 days, which is about 3.8 months. So, every 4 months OCI sounds reasonably safe. I drive about 1000 miles a month, so 4 months/4000 miles OCI.

I understand there are many other factors that can affect the oil life but is my formula good enough for a rough estimate?

My car doesn't have an OLM and my driving conditions do not fall 100% either in the Severe or the Normal category. I do mainly highway about 80% and you know sometimes, the highway is jammed and those occurrences should be considered Severe. I just want to figure out a good balance for me in terms of OCI.

Thoughts on my estimation formula?

 

[NateDN10]

To me that seems overly cautious. You say 80% highway, but 4 mo./4000 mi. is definitely skewed toward the severe end of the recommended schedule.

Why not do a weighted average based on city/hwy mileage:
OCI = (hwy %) * 7500 + (city %) * 3000

Given 80% highway, that would give you a 6600 mi. OCI.

Just my opinion.

 

[Bill in Utah]

What type of vehicle? Force fed? Warranty concerns?

 

[willix]

To have a hour meter would indicate another way to gauge your intended OCI by monitoring time vs miles differences in your routine. I think 200 hrs would be early.

Your "easy driving" & "severe" driving probably balance out be close to "normal".

4000mi seems to be short, premature.

 

[barlowc]

And what kind of oil, conventional or synthetic?

 

[Gary Allan]

Are you sure that's not 6months/7500? 7500 as a daily driver over one year would surely mean hostile conditions in my book.

Based on a 5.5 day week, that would mean that the mean event would be 13 miles long (one way). If it was used more days, that would reduce it even more.


Track your average fuel economy then do one UOA to index you to the level of fatigue you're experiencing. You should then be able to noddle that around to a given mileage for a given overall average.

Your traffic jams aren't severe beyond having a hard time keeping track of the fuel usage. There's no way to record the operation on an odometer that doesn't move. It's not hard on the engine. It's not hard on the oil.

 

[iExcel]

Originally Posted By: Bill in Utah
What type of vehicle? Force fed? Warranty concerns?
It's a Chevy Malibu 2003. No warranty concerns.

 

[iExcel]

Originally Posted By: barlowc
And what kind of oil, conventional or synthetic?
Conventional 5W30. usually FS sometimes GTX.

 

[iExcel]

Originally Posted By: Gary Allan
Are you sure that's not 6months/7500? 7500 as a daily driver over one year would surely mean hostile conditions in my book.
Yes, I am sure 12mth/7500 is what's written on my owner's manual. I even double checked it before posting this topic.

 

[Bill in Utah]

Originally Posted By: iExcel
Originally Posted By: Bill in Utah
What type of vehicle? Force fed? Warranty concerns?
It's a Chevy Malibu 2003. No warranty concerns.


Follow the OLM with any 5w30 and you are set. (I'm sure it has one?)

Bill

 

[iExcel]

Originally Posted By: Bill in Utah
Originally Posted By: iExcel
Originally Posted By: Bill in Utah
What type of vehicle? Force fed? Warranty concerns?
It's a Chevy Malibu 2003. No warranty concerns.


Follow the OLM with any 5w30 and you are set. (I'm sure it has one?)

Bill
Unfortunately, no it doesn't have one.

I believe GM started to install OLMs on malibus after 2004.

 

[willix]

this 04 has OLM. 2004 malibu

 

[Gary Allan]

Originally Posted By: iExcel
Originally Posted By: Gary Allan
Are you sure that's not 6months/7500? 7500 as a daily driver over one year would surely mean hostile conditions in my book.
Yes, I am sure 12mth/7500 is what's written on my owner's manual. I even double checked it before posting this topic.


I have a hard time believing that it's correct.

 

[iExcel]

Originally Posted By: Gary Allan
Originally Posted By: iExcel
Originally Posted By: Gary Allan
Are you sure that's not 6months/7500? 7500 as a daily driver over one year would surely mean hostile conditions in my book.
Yes, I am sure 12mth/7500 is what's written on my owner's manual. I even double checked it before posting this topic.


I have a hard time believing that it's correct.
This is a direct copy/paste from the manual.

Quote:

Long Trip/Highway Scheduled Maintenance

7,500 Miles (12 500 km)
0 Change engine oil and filter (or every 12 months,
whichever occurs first). An Emission Control
Service.
0 Rotate tires. See Tire Inspection and Rotation on
page 5-54 for proper rotation pattern and additional
information. (See footnote +.)

 

[Gary Allan]

Oh, I believe you see that written there. But I KNOW there are several million units that specify 7500/6months with ONE YEAR on the filter if the mileage is used to determine the OCI.


Here's where you would run into a contradiction with your two service recommendations.

If would be totally possible to have your 3k fall EXACTLY on 3m. If so, then you would be doing 12k/12m with 4 service points.

Anyone doing 12k/year is typically not in severe service.

 

[iExcel]

I'm attempted to do 5k OCI based on my driving conditions and it seems it should be quite doable for non-winter seasons. For the Canadian Winter here, I'm thinking of putting in some home-made synthetic blend with 1/3 synthetic (Amsoil XL or PP) and 2/3 regular stuff (FS, GTX). and still do 5k OCI. Is this a good guess or the synthetic is not really needed?

btw, the sump is 4.5 qt and the engine is the GM 3.1L with the LIMG fixed.