so qts x 50 x mpg?
Calculating OCI
- Thread starter ka9mnx
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so qts x 50 x mpg?
glad you noticed it too... at first I thought they meant (qts x 200) / (4 x mpg) but that makes even less sense.
city driving, or every severe service increases the fuel consumption.
Yes I understand given the same vehicle, that makes sense.
But why should a Corolla with a 4 cylinder that gets 50mpg be double than say a Rav4 that gets 30mpg? Same sump approximately?
the rav4 with the same engine getting 30mpg is working harder.
Your valve cover being off doesn't show you the piston ring deposits, looked clean to you? that can be taken in many different ways, 1ZZ are known oil burners, and you want to talk about the era 1MZ-FE are known sludge monsters.And the real world implications for (theoretically) not being as clean as it could / would be, (besides looking cleaner), is? Because I had the valve cover off my 1ZZ earlier this year. It looked clean to me.Then again, I followed the manufacturer's recommended interval, not the interval displayed on some full synthetic oil jug.
Toyota engineered this era of motors to run on pure Dino oil at 6mo/5k intervals. Even using the modern synthetic blend oils available today is pampering these motors.
I guess someone should tell The Car Care Nut he is missing a huge opportunity by not offering and upselling oils in his shop.
Full synthetic resists oxidation better, it resists breakdown better, it resists sludge, deposits and varnish better especially deposits on piston rings, this is just basic facts.
The Car Care Nut can run his shop how he wants, again he is a Toyota purest and that is his choice.
You do you, full synthetic is still superior.
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- Jul 18, 2025
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(qts x 200) / (4 x mpg) = X
With brackets it makes sense. The 50 instead of 200/4 guys need to go back to school.
If you remove the brackets and then follow BODMAS then 50 makes sense. With brackets you don't get 13,000 miles. This formulae is all over the place. You need to fight the correct formulae.
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Maybe. But if the thermal management is working its not working the oil any harder?
How about a belt vs chain (higher shear). How about DI vs MPI. Why is average oil temp not in the formula? Does it have an oil cooler or not?
Seems like you would be better off to simply follow your manual.
the oil gets exposed to more blowby if there's more consumption, it does degrade faster.
shear should be adressed by initial viscosity. di can run less fuel through an engine than mpi.
I don't agree with the formula above, but fuel used IS a very good metric, I'm sure it's part of many oil life monitors.
Early 1ZZ were oil burners due to engineering defects (that were eventually corrected in later models). Oil used had little to no influence.
I don't think the debate was that full synthetic isn't superior. Toyota genuine 5w30 is an API SP, SN Plus, SN oil. Nowhere on the bottle does it even mention the terms "synthetic", "blend", or "conventional". Presumably because it doesn't matter. The oil meets manufacturer specs to be run for manufacturer recommended 5k intervals. Just because it may be a synthetic blend and not a full synthetic doesn't mean it isn't good enough or incapable of going 5k intervals long term.
I didn't say it wasn't capable of doing 5K intervals long term, full synthetic is simply superior at it and in regards to deposits, varnish, oxidation, sludge, oil breakdown even extreme temperatures this is just an undeniable fact.
Run what you want.
This video is a good example (Conventional is Synthetic Blend)
I almost used number of spark plugs as a divider, then I remembered the dual plug motors (Dodge and I think a Ford?)--then remembered the plug spitting Fords. Decided con rods was probably more right... except for you guys who like to install inspection ports!
You said you wouldn't run a synthetic blend for 5k. I assume that's because you think it wouldn't be good enough. (Perhaps a wrong assumption on my part to assume that.)
Anyways, yes, I've seen that video. But, there's a MAJOR problem with how they ran that test. The conventional / blend was run for 10k intervals. Conventionals / blends (as we are discussing with Toyota 5w30) are specced for 5k intervals by the manufacturer, not 10k. So, of course the conventional / blend does worse. Rerun the test changing the conventional / blend every 5k miles instead of 10k miles and I bet we see much different results.
You didn't look at the formula correctly.
I should have done it this way (qts x 200) / (4 x mpg) = OK?
Actually, on a trip, it gets 20-22 mpg.
That doesn't make sense—by adding those brackets, getting better mileage would make the OCI shorter. Getting better mileage should mean a longer interval: less fuel has run through the motor (dilution) and car likely spent more time on the highway (inherently less wear and tear). I think the formula is meant to be qts * 50 * mpg = OCI. For my E90 BMW with a 7 qt sump that averages 20 mpg, 7000k changes seems about right.
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A couple times a year if it needs it or not
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