Oil life Rule of Thumb from another forum. Good advice?

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Point taken but as an example my CX5 gets 32-33mpg on the highway. That could drop to 27 in city for example but the result would still be a long OCI in my view. Now that is a personal opinion on my part and not scientific in any way.

It is a good point though.
I hear ya. Difference between 32-33 and 27 mpg isn't all that much. But on the other hand, if you're still getting 27 mpg in the city, then maybe your city driving isn't all that hard core, so maybe it doesn't call for shortening the OCI that much. Now, if you were in some really bad back-to-back traffic with lots of idling, I'm sure your MPG would be significantly worse.

Google Docs BITOG OCI Calculator link
 
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It's a logical concept, not perfect, but makes a lot more sense that a fixed distance. The specific numbers need to be adjusted to the particular vehicle and oil.

As is, the formula gives me about 11,500 miles, vs. 10,000 recommended by Toyota, vs. roughly 8,800 I typically actually go.
 
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These blanket type estimates don’t work for everyone. It depends on driving conditions, length of travel, speeds, and so forth.

Since the OP is from the Philippines he could use the example of traffic in Manila which is some of the worst in the world. Would he go 10,000 km between oil changes driving that every day in a turbo GDI engined vehicle?

Just for clarity I have been to Manila and I can attest to the severity of the traffic.

the traffic might be bad, but dayum they make some nice folders over there!
 

leoblack9

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These blanket type estimates don’t work for everyone. It depends on driving conditions, length of travel, speeds, and so forth.

Since the OP is from the Philippines he could use the example of traffic in Manila which is some of the worst in the world. Would he go 10,000 km between oil changes driving that every day in a turbo GDI engined vehicle?

Just for clarity I have been to Manila and I can attest to the severity of the traffic.
Yeah traffic here is absolutely terrible. The rule of thumb that everyone follows here is 10,000km or 6300mi maximum if using synthetic.

Using the formula my diesel Toyota (Fortuner which is a common rail 2.5L turbocharged unit) gets 16.45mpg in absolutely horrible Manila traffic; has a 7.5L sump (oil pan + oversized Fram ultra xg3600) equals 6172mi or 9875km. Pretty near the hard 10,000km rule.

Food here is great if you have a thing for rice meals, bulalo and sisig ftw.
 
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For many new vehicles, proper oil choice and frequent oil changes are exceedingly important. There is a reason many modern engines trash a timing chain at less than 100,000 miles, on the OEM oil and change interval. From Ford's 3.5, 3.7, 5.4 and others, Chevy's 3.0 and 3.6, various Dodge engines, BMW's and yes, even some Toyota engines. Not to mention cam phaser problems, bearing problems, balancer chain problems and so on.

It remains a wise thing to understand what engine you operate, and to know whether it's subject to rapid wear issues using the OEM oil and change intervals. On many of the above mentioned engines, a timing change job is $4500.
I attribute having zero VVT or timing chain issues with my wife's 5.4 Triton in over 220k miles to a lifetime of 5k oil changes instead of the factory recommended 7.5K mile OCI. Knock on wood.
 
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For many new vehicles, proper oil choice and frequent oil changes are exceedingly important. There is a reason many modern engines trash a timing chain at less than 100,000 miles, on the OEM oil and change interval. From Ford's 3.5, 3.7, 5.4 and others, Chevy's 3.0 and 3.6, various Dodge engines, BMW's and yes, even some Toyota engines. Not to mention cam phaser problems, bearing problems, balancer chain problems and so on.

It remains a wise thing to understand what engine you operate, and to know whether it's subject to rapid wear issues using the OEM oil and change intervals. On many of the above mentioned engines, a timing change job is $4500.

Especially with GDI/TGDI. Lots of Ford's sludged up at high mileage following the recommended interval. For the first 100k of my GDI Hyundai's life I did 5k intervals and still ended up with some minor deposits (most of which have been removed with shorter intervals, seafoam, and a few ester based oil changes).

Any small displacement, high output GDI or TGDI engine I own in the future will be getting 3-4k intervals, especially if it's got a small sump.
 
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Change it at the interval the owner's manual says or when the oil-life monitor/indicator in the vehicle says. Only a tiny % of street vehicles use oil analysis labs and are by no means necessary. Even some people who use labs still ignore (or don't "trust") the mileage intervals they recommend or say can be used.

My F150 says 10k miles.
That’s scary AF to me.
 
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I like the formula. I cannot figure out the second formula but the first formula results in 5,500 miles. I change the oil between 5 and 6K (once a year). Toyota says 7,500 miles.
 
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My F150 says 10k miles.
That’s scary AF to me.
Why, you think Ford didn't test it extensively and are confident that it's completely safe for the engine ? They have no interest in destroying engines that in many cases will need replaced under warranty, i.e. on their dime.
 
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I cannot figure out the second formula
Take your oil sump capacity and multiply it by 200 to get the total amount of fuel burned. For example, if your oil capacity is 5 quarts, then 5x200 = 1,000 quarts of fuel, or 250 gallons. Now multiply this amount by your MPG to get the OCI. Say your MPG is 23, so 250x23 = 5,750 miles OCI.

So, to summarize, the formula is:
OCI (miles) = Oil sump capacity (quarts) x 50 x MPG

It's basically the same as the first formula.

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.
 
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leoblack9

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@quattro, that's OCI calculator very helpful! This is more in line with my expectations.

I'm also using amsoil's 5w30 diesel max duty ss, need to consider that too.
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Why, you think Ford didn't test it extensively and are confident that it's completely safe for the engine ? They have no interest in destroying engines that in many cases will need replaced under warranty, i.e. on their dime.
Sure, but do they have a vested interest in engines that last several times the warranty period, or would they prefer you to buy a new truck before then?
 
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Sure, but do they have a vested interest in engines that last several times the warranty period, or would they prefer you to buy a new truck before then?

Designed life of just about every vehicle is 150k miles. The OCI is set to make it at least that far.
 
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