Oil Change Interval Calculator

Interesting formula I came across on www.bobistheoilguy.com

OCI (miles) = Oil sump capacity (quarts) x 50 x MPG

BTW, here is TooSlick's formula which is more elaborate/refined as it also takes into account oil's starting TBN, engine displacement, and engine HP:
OCI (miles) = 0.8 x TBN x TBN x MPG x oil sump capacity (quarts) x engine displacement (liters) x 61.0237 / engine horsepower (HP)

You don't have to do the math. Instead you can just use the Google Docs calculator I linked to earlier.


Google Speadsheet Oil Change Calculator

Yes, I know there is a built in oil change reminder, but I was planning on doing 5,000 mile changes and this ends up pretty close to that range. Not here to start a debate, just an interesting tool to play around with.

Good info, Thanks!

This is too complicated so early in the morning.

So you have an oil change reminder built into the vehicle, plus you already know that you want to change the oil at 5k regardless, yet you broke out the chalkboard for this one?

Lucky said:

So you have an oil change reminder built into the vehicle, plus you already know that you want to change the oil at 5k regardless, yet you broke out the chalkboard for this one?

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You can never be too paranoid

drew707 said:

You can never be too paranoid

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Yes you can

*triggers ex-girlfriend PTSD*

Cool. Thanks

Lucky said:

So you have an oil change reminder built into the vehicle, plus you already know that you want to change the oil at 5k regardless, yet you broke out the chalkboard for this one?

Click to expand...

Some people are just data-analytic wired. Nothing wrong with that. He's just presenting the science behind the reasoning

You can very safely ignore this calculator. It doesn't mean anything and the calculator has no stake in the health of your engine, so there's no incentive to get anything correct. The calculator doesn't measure anything on your engine and there's no recourse if you've trusted the calculator and it went wrong.

Use oil that meets Ford's spec (WSS-M2C961-A1). Change it per the vehicle's oil life monitor, or earlier if you want. And if you want to get really crazy, capture and send in a sample of your oil for analysis. This will actually tell you if the viscosity is breaking down, if you have contaminants, if you're seeing excessive wear.

Always appreciate the passionate Bronco owners that take extra care and time to make sure their beasts stick around for a long time. Nothing wrong with that!! This is why we still see vintage Bronco’s on the road! All about the maintenance.

There’s a chart in the owners manual that recommends intervals based on driving style and vehicle use.

Turbo engines need the oil changed more often.

Lucky said:

So you have an oil change reminder built into the vehicle, plus you already know that you want to change the oil at 5k regardless, yet you broke out the chalkboard for this one?

Click to expand...

Not my formulas. Like I said, I found it to be an interesting tool that works on a wide range of vehicles. Using my truck specs and oil specs the numbers landed pretty close to my 5,000 mile plan. I had no intentions of following the built-in oil life monitor. I didn't expect this to get stickied and know that oil discussion tends to be polarizing. Do what you want. There is a documented case of a 2.7 running 400k+ miles going by the oil life monitor and motorcraft semi synthetic.

https://www.f150forum.com/f118/465-000-mile-2-7-a-389552/

I thought Ford engineered it so that you get an oil change the next time you take it in for top leaks, swells, or cracks.