OCI Formula

[The Critic]

https://bobistheoilguy.com/forums/t...ultimate-oil-change-strategy.2637/#post-35025

@TooSlick came up with this formula many years ago. A few of us were around when this formula was discussed. Curious if anyone still uses it or feels it is relevant in this current environment.

Formula: OCI = (C*)(ave mpg)(sump in qts)(cubic inches/Hp)
C= constant which was derived by Tooslick's opinion from reviewing UOA's; he was using a "120" for Amsoil and "80" for synthetic oils such as Mobil 1.

 

[The Critic]

Based on the formula, I am coming up with a ~7,800 mile interval using "80" as a constant for "C" on my HEMI.

(80) * 16 mpg * 7-qt * (345/395) = 7,822.08

 

[Quattro Pete]

We've added it (along with few other methods) to an online calculator a while back. I still plug numbers into it sometimes, just for S&G.

https://docs.google.com/spreadsheets/d/1VChJk6rO-Wocwor_7_mpnGEyiCCuEmz9FaPtbcEhIC8

 

[JeffKeryk]

Michael, all my calculations come up with 5,000. Plus or minus...

 

[Vercingetorix]

Friend of mine in high school had a great formula for picking oil brands. Yellow car gets pennzoil, green car Quaker state, silver car Mobil 1etc. Worked every time.

 

[The Critic]

Friend of mine in high school had a great formula for picking oil brands. Yellow car gets pennzoil, green car Quaker state, silver car Mobil 1etc. Worked every time.

That's genius, but I cannot think of an oil for my dark grey Prius. Or the sky blue Accord.

 

[Quattro Pete]

TooSlick's formula actually comes up with a very similar result to what FCA recommends for my SRT - about 6,000 mile OCI.

Interestingly enough, the OLM in my old 530i is fuel consumption based as well, alas, the parameters chosen are a bit too lenient, at least for my short-tripping driving patterns. It basically expects you to burn through 627 gallons (2,375 liters) of fuel before asking for an oil change. Time is not factored in. If you average 24 MPG, that ends up being a 15k mile OCI. Likely doable in mostly hwy driving, for someone who drives a lot and racks up miles quickly. Ted's formula says 11K miles under those conditions.

 

[The Critic]

TooSlick's formula actually comes up with a very similar result to what FCA recommends for my SRT - about 6,000 mile OCI.

Does yours have a OLM?

The OLM on my truck has me on-track for a 10K interval.

 

[Quattro Pete]

Does yours have a OLM?

It does, but I drive so little, I don't come anywhere close to hitting it. I believe it's scaled for 6K intervals.
The OM says 6K miles or 6 months max, whichever comes first.

 

[FatCat2]

I was ready to laugh at the equation but it gives me 4,800 miles / 8 months for tuned EcoBoost F150. And 4,900 for the stock Explorer ST with 3.0 EcoBoost.

Guess the ole 5k will do

 

[tarbe]

No factor for diesel vs gas?

 

[OVERKILL]

Gave me 4,600 for the Jeep.

 

[incognito_2u]

That's genius, but I cannot think of an oil for my dark grey Prius. Or the sky blue Accord.

Havoline Pro DS and SuperTech......

 

[blufeb95]

That's genius, but I cannot think of an oil for my dark grey Prius. Or the sky blue Accord.

Delo XLE for the Prius

 

[The Critic]

Havoline Pro DS and SuperTech......

Delo XLE for the Prius

Good point, I had forgotten about those two. I have Supertech synthetic in my garage but it is in the white 12-qt boxes. Havoline ProDS is in the brown 6-qt boxes.

 

[AutoMechanic]

If I remember correctly one type of Liqui Moly has a sky blue bottle.
Yes they do found it.

 

[The Critic]

If I remember correctly one type of Liqui Moly has a sky blue bottle.

Good memory.

 

[Benzadmiral]

The OCI Calculator gives me 4800 miles based on mpg, and 6900 mi./9 months average. I pretty much do the former anyway.

 

[BeerCan]

results for my truck

 

[Benzadmiral]

The OCI Calculator gives me 4800 miles based on mpg, and 6900 mi./9 months average. I pretty much do the former anyway.

I think the TBN for Castrol Magnatec 5w30 is 11 instead of the proposed 7.9. So the OCI calculator now gives me 9400 miles based on mpg, and the average is 9500 mi./12 mos.