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#4626547 - 01/07/18 01:16 AM Using fuel use to determine oil change interval
CharlieBauer Offline


Registered: 03/29/16
Posts: 1177
Loc: CA
I've seen it mentioned many times that using fuel consumed to determine when to change oil is a possible method along with hours and miles.

So what exactly is the formula here?

I presume we need:

Gallons of fuel consumed
Sump size
Engine size

Once we have that info, what calculation do we perform?
_________________________
It ain't what you don't know that gets you into trouble. It's what you know for sure that ain't so.

- mistakenly attributed to Mark Twain

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#4626563 - 01/07/18 02:29 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
Shannow Offline


Registered: 12/12/02
Posts: 39871
Loc: 'Stralia
I've been here WAY too long and remember too much of it...
https://bobistheoilguy.com/forums/ubbthreads.php/topics/35025/Re:_Kublin_Method--the_ultimat#Post35025

Originally Posted By: TooSlick
Rexman,

The oil change formula posted over on the 3MP is NOT the correct one. This is the actual formula I developed:

OCI = (C*)(ave mpg)(sump in qts)(cubic inches/Hp)

Where C* is a constant which was derived by looking at oil analysis data I've accumulated over the last 10 years. For Amsoil I use a C* of 120, which generates drain intervals of approx 7500 miles for a turbo or motorcycle, up to 15k-20k for a low power density engine driven easily on the highway. If you have an application where you are dirt or soot limited, you can't use this formula and get a good estimation of oil life.

You CANNOT use the TBN times ten as a substitute for this C* value. The rate of TBN depletion varies significantly depending on the quality of basestock and additive chemistry. In addition, TBN depletion is non-linear, as you have seen from the 3MP tests. In other words, a 6 TBN oil will not last 50% as long as a 12 TBN synthetic. In actual practice, it might only last 25%-33% as long.

I don't have as much data on other oils as I do with Amsoil in deriving additional C* values. For Mobil 1 I suggested using a C* of 80, based on the limited data I've seen on this site. For an average quality petroleum lube, I think a C* of 40 is reasonable. The implication of using these various C* values is easy to see ....

Please feel free to contact me off-line if you have any other questions about this OCI formula. BTW, I've made my living as a propulsion engineer for the past twenty years - the Amsoil stuff is something I do on the side.

Tooslick.
Dixie Synthetics


Ted was an Amsoil dealer fyi.

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#4626564 - 01/07/18 02:31 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
OneEyeJack Offline


Registered: 09/14/10
Posts: 7479
Loc: S California
Work out your own formula. Example?

My 2003 4Runner V8 Avg MPG=19 (current average over all kinds of driving that I normally do)

10,000-mile OCI Current OCI

10,000 miles/19 avg mpg = 526(rounded off) gallons of gasoline. Insert some fudge factor.

Change oil every 500 gallons of gasoline.

Current UOA with 10,000 OCI

My situation is very constant so I just do my OCI by mileage otherwise I'd work up a gasoline use formula. If I lived where there was a big change in the weather from summer to winter I'd probably use such a formula.

If you did idle the engine more or work it harder towing or off-roading you'll use up 500 gallons sooner mileage wise so you'll automatically be adjusting the OCI.

If this makes any sense to you then you can figure out your own formula and check it with a UOA.

A friend that has a dozen or so service trucks that service microwave towers, some or most of them in very difficult areas to reach so he uses such a formula. He's been doing it this way for over 25 years and his results are excellent. He started with a nominal interval of 5000 miles to create a formula for each truck and now some trucks get an oil change and other services at less than 3000 miles depending on conditions. A couple of his trucks have power-takeoffs that run all day long and this system compensates for that. UOA's prove that this system works for him.

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#4626566 - 01/07/18 02:33 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
Shannow Offline


Registered: 12/12/02
Posts: 39871
Loc: 'Stralia
Gives 11,000 miles for my Colorado using the M1 number.

Holden say 15,000km 9,300 miles. However with my driving style, the OLM looks like it's heading for 11,000 miles plus a bit.

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#4626576 - 01/07/18 03:15 AM Re: Using fuel use to determine oil change interval [Re: Shannow]
CharlieBauer Offline


Registered: 03/29/16
Posts: 1177
Loc: CA
Originally Posted By: Shannow
I've been here WAY too long and remember too much of it...
https://bobistheoilguy.com/forums/ubbthreads.php/topics/35025/Re:_Kublin_Method--the_ultimat#Post35025

Originally Posted By: TooSlick
Rexman,

The oil change formula posted over on the 3MP is NOT the correct one. This is the actual formula I developed:

OCI = (C*)(ave mpg)(sump in qts)(cubic inches/Hp)

Where C* is a constant which was derived by looking at oil analysis data I've accumulated over the last 10 years. For Amsoil I use a C* of 120, which generates drain intervals of approx 7500 miles for a turbo or motorcycle, up to 15k-20k for a low power density engine driven easily on the highway. If you have an application where you are dirt or soot limited, you can't use this formula and get a good estimation of oil life.

You CANNOT use the TBN times ten as a substitute for this C* value. The rate of TBN depletion varies significantly depending on the quality of basestock and additive chemistry. In addition, TBN depletion is non-linear, as you have seen from the 3MP tests. In other words, a 6 TBN oil will not last 50% as long as a 12 TBN synthetic. In actual practice, it might only last 25%-33% as long.

I don't have as much data on other oils as I do with Amsoil in deriving additional C* values. For Mobil 1 I suggested using a C* of 80, based on the limited data I've seen on this site. For an average quality petroleum lube, I think a C* of 40 is reasonable. The implication of using these various C* values is easy to see ....

Please feel free to contact me off-line if you have any other questions about this OCI formula. BTW, I've made my living as a propulsion engineer for the past twenty years - the Amsoil stuff is something I do on the side.

Tooslick.
Dixie Synthetics


Ted was an Amsoil dealer fyi.


Thanks for that.

It's certainly interesting and the "C" is everything really.

Funny how he essentially says you can run synthetic twice as long as conventional and amsoil three times as long as conventional.
_________________________
It ain't what you don't know that gets you into trouble. It's what you know for sure that ain't so.

- mistakenly attributed to Mark Twain

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#4626695 - 01/07/18 08:56 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
Audios Offline


Registered: 11/19/11
Posts: 887
Loc: Lyndhurst NJ
On the older BMWs, say 1999-2006 when you would reset the interval it would blink 3250L, which means 3250 liters of fuel. That works out to about 860 gallons of gas, and using my 15 mpg avg on my x3, (shorter trips, wife driving, loves to warm it up for a while, wasteful) would have an interval of about 12,800 miles, with the yellow or flashing warning starting at about 10k. The higher performance M cars resets to the same fuel interval, but their likely worse fuel economy will bring that interval down to around 10k. Some people with more highway miles and averaging 18 miles per gallon would be able to go almost 15,500, which is the limit per BMW.
_________________________
2002 VW Golf TDI-Mobil 1 5/40 TDT
2005 BMW M3 BMW Twin Power 10/60
1998 BMW M3/4/5 Fuchs 5/40
2007 Mercedes GL320 CDI Fuchs 5/40 GT Pro XTL

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#4626847 - 01/07/18 11:46 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
Linctex Offline


Registered: 12/31/16
Posts: 6148
Loc: Waco, TX
Makes you wonder what info is used to create the algorithms that are used for "Oil Life Monitor" calculations

Probably something pretty similar.
_________________________
"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."

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#4626867 - 01/07/18 11:55 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
shanneba Online   content


Registered: 07/10/04
Posts: 887
Loc: Indiana (IN)
In June of 2000 BMW changed the E46 3 series Service Interval (oil life) Information monitor to be based on gallons of gas used.
7 quart sump, 2.3,2.5.2.8 or 3 liter engines.

Using a 328i as an example:
Standard transmission model: SII
illuminates after consumption of
601 gallons of fuel.
Automatic transmission model: SII
illuminates after consumption of
667 gallons.

The miles to service displayed was based on a 25 mpg average when the originally reset, typically ~15,500 miles.
Different driving conditions (mpg) would give different intervals.
They may have varied the gallons based on the displacement, I don't know for sure.


Edited by shanneba (01/07/18 12:01 PM)
_________________________
2003 BMW 330Ci
2013 HD Sportster XL1200C

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#4626949 - 01/07/18 01:16 PM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
Nitronoise Offline


Registered: 03/24/10
Posts: 488
Loc: Chicago Suburbs
I was looking at some auction vehicles in appleton wi , they say they use 600 gallons of fuel to dictate the oil change on police and public service vehicles as squads do a lot of idling
_________________________
07 Ford Freestyle 135K
04 Hyundai Sonata 280K
03 Hyundai Santa Fe 165K
02 Ford Tarus 98K
00 Buick Regal SC 135K
95 Goldwing 28K


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#4627365 - 01/07/18 07:34 PM Re: Using fuel use to determine oil change interval [Re: Linctex]
CharlieBauer Offline


Registered: 03/29/16
Posts: 1177
Loc: CA
Originally Posted By: Linctex
Makes you wonder what info is used to create the algorithms that are used for "Oil Life Monitor" calculations

Probably something pretty similar.


Nope, it is far more advanced including the work put in to arrive at it.

Check bbobynski's posts back in 2005. I found them yesterday and they're amongst the best stuff I've read here.

https://bobistheoilguy.com/forums/ubbthreads.php/ubb/userposts/id/6718
_________________________
It ain't what you don't know that gets you into trouble. It's what you know for sure that ain't so.

- mistakenly attributed to Mark Twain

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#4627405 - 01/07/18 08:02 PM Re: Using fuel use to determine oil change interval [Re: Shannow]
Garak Offline


Registered: 12/05/09
Posts: 24586
Loc: Regina, Saskatchewan, Canada
Wasn't there another algorithm of some sort, a little more recently? I just can't think of the poster off the top of my head.
_________________________
Plain, simple Garak.

2008 Infiniti G37 - Shell ROTELLA T6 Multi-Vehicle 5w-30, NAPA Gold 7356
1984 F-150 4.9L - Quaker State GB 10w-30, Wix 51515

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#4627513 - 01/07/18 09:10 PM Re: Using fuel use to determine oil change interval [Re: Shannow]
CharlieBauer Offline


Registered: 03/29/16
Posts: 1177
Loc: CA
Originally Posted By: Shannow
Gives 11,000 miles for my Colorado using the M1 number.

Holden say 15,000km 9,300 miles. However with my driving style, the OLM looks like it's heading for 11,000 miles plus a bit.


It's interesting that the formula takes you to a similar point as the OLM if you assume M1.

But isn't the OLM in Australia calibrated for conventional oil, in which case the formula might have you as low as 5,500 miles?

My own retrospective calculation for a (full syn) oci where I have a UOA and have to guesstimate the mpg, gives me something that seems in the right ballpark too.

I do think that assuming C=40 for conventional is too low as that seems to make manufacturer recommended ocis too long.
_________________________
It ain't what you don't know that gets you into trouble. It's what you know for sure that ain't so.

- mistakenly attributed to Mark Twain

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#4627727 - 01/08/18 05:03 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
Shannow Offline


Registered: 12/12/02
Posts: 39871
Loc: 'Stralia
Originally Posted By: CharlieBauer

But isn't the OLM in Australia calibrated for conventional oil, in which case the formula might have you as low as 5,500 miles?


C3/Dexos 2 5W30 is specified by the manuals...So yes, any dino that meets those three specs would give the same result on the oil life monitor.

Of course I could throw in SAE30 small engine oil and it would tell me exactly the same answer, as it's assuming that I've used the specified oil in the first place, isn't it ?

The wagon trains that deliver Colorados to Australia are capable of carrying oil too...even synthetics.

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#4627730 - 01/08/18 05:10 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
CharlieBauer Offline


Registered: 03/29/16
Posts: 1177
Loc: CA
The point I'm making is the fuel consumption formula in your case is way off if C is set to 40 for conventional.
_________________________
It ain't what you don't know that gets you into trouble. It's what you know for sure that ain't so.

- mistakenly attributed to Mark Twain

Top
#4627737 - 01/08/18 05:22 AM Re: Using fuel use to determine oil change interval [Re: CharlieBauer]
Shannow Offline


Registered: 12/12/02
Posts: 39871
Loc: 'Stralia
Originally Posted By: CharlieBauer
The point I'm making is the fuel consumption formula in your case is way off if C is set to 40 for conventional.


OF COURSE IT IS OFF IF YOU SET C FOR 40 (conventional).

Your statement was...

Originally Posted By: CharlieBauer

But isn't the OLM in Australia calibrated for conventional oil, in which case the formula might have you as low as 5,500 miles?


I don't know, I didn't calibrate it...did you ?

GM specify ACEA C3, or DEXOS2, an in grade 5W30...

Holden (GM) seem to be implying a synthetic here, aren't they ???



Edited by Shannow (01/08/18 05:23 AM)

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