Small sump = shorter OCI?

[AZjeff]

I've been comfortable with 5K OCIs on my vehicles with 5 quart sumps. This Xterra 3.3L has a 3.5 qt sump, 30% less than "normal". My poor logic tells me in 3500 miles the oil sees the same amount of work as 5 qts of oil @ 5000 miles. Make sense?

 

[bdcardinal]

I hate small oil sumps. Part of the reason Ford went with a 8 quart sump on the 5.0 Coyote was to extend the OCI out to 10K miles.

 

[Quattro Pete]

There is more to OCI than just sump capacity, but it does factor into the overall equation.

You can play around with this calculator we put together a while back:

https://docs.google.com/spreadsheets/d/1VChJk6rO-Wocwor_7_mpnGEyiCCuEmz9FaPtbcEhIC8/edit?pli=1#gid=4

 

[Chris142]

Makes sense to me

 

[zach1900]

My not even 3qt Sentra didn't seem to mind a small sump on dino 7k oci on dino at best lax oil changes. I gave it away at 300,000 with zero engine problems. More oil means more likely more will remain cold.

 

[zach1900]

Only a certain amount of oil can actually be in the engine at any given time anyway.

 

[Quattro Pete]

Originally Posted By: zach1900
Only a certain amount of oil can actually be in the engine at any given time anyway.

Sure, and what isn't, is not getting beaten up by the engine and is not being depleted of additives. Plus, the acids produced by the engine can be diluted in a larger pool of oil. So yes, more oil can help with longer OCIs.

 

[zach1900]

Why not make a 4cylinder have a 50 qt Sump heck why not 50 gallons. You could carry a drum on the roof of your Corolla.

 

[Quattro Pete]

Originally Posted By: zach1900
More oil means more likely more will remain cold.

Vehicles with larger sumps have their cooling/heating systems designed accordingly so that they don't take forever to reach operating temp.

 

[Quattro Pete]

Originally Posted By: zach1900
Why not make a 4cylinder have a 50 qt Sump heck why not 50 gallons. You could carry a drum on the roof of your Corolla.

Why not stop being ridiculous?

 

[zach1900]

Okay maybe the Japanese are better at making the most out of a "small" sump. Hundreds of thousands of miles between 3 Nissans with barely 3-4 qt sumps. Never an issue.

 

[Quattro Pete]

Originally Posted By: zach1900
Okay maybe the Japanese are better at making the most out of a "small" sump. Hundreds of thousands of miles between 3 Nissans with barely 3-4 qt sumps. Never an issue.

Nobody says there is an issue. But if one wanted to run 10-15-20K mile OCI, larger sump can certainly help.

 

[A_Harman]

If you're short-tripping, the small sump will allow the oil to heat up more quickly, so it's not all bad.

 

[ccap41]

Originally Posted By: bdcardinal
I hate small oil sumps. Part of the reason Ford went with a 8 quart sump on the 5.0 Coyote was to extend the OCI out to 10K miles.


Yeah, same with a lot of Mercedes and BMW are all 7.5-9.0, I believe. And they all have 10,000 mile intervals. I guess I'm not up to date on my 2013+ stuff but the early 2000's- about 2013 were all like that. I think the AMGs were the only ones over 8.5 and 8.5 was the norm.

 

[camrydriver111]

Maybe you can buy an aftermarket oil pan to increase your volume?

If not I would consider getting a custom one made.

 

[rslifkin]

Assuming all other factors are equal (same engine in the same vehicle with the same usage patterns), a smaller sump will have a shorter OCI.

In the real world, sump size isn't the only thing dictating OCI length, although vehicles with long factory OCIs do tend to have larger sumps.

 

[turtlevette]

Originally Posted By: A_Harman
If you're short-tripping, the small sump will allow the oil to heat up more quickly, so it's not all bad.


The short tripping thing is way overblown.

 

[Doog]

Just use synthetic oil and you are fine.

 

[Jetronic]

the mitsubishi outlander diesel had a 5.5 quart sump when the oci was 15000 km (around 9k miles)

when the oci changed to 12k miles for newer vehicles, the sump went to 7.75 quarts.

then there's my car, 4.5 quart sump and 22k oci....also diesel

 

[Shannow]

Have read a bunch of papers that show that the oil in the ring belt gets depleted of anti-oxidants in it's stay there...which is tens of seconds at 200-250C, and bathed in reactive blowby gasses.

It makes sense that a larger sump, with less trips to the ring belt would/could have a longer life...all other things being equal.

Your logic is sound, but I firmly believe that your 5K oil in the 5qt sump is nowhere near exhausted at the end of the 5K...say it's only 50% "done", which is reasonable, then the 3.5 is good for 7K, and 5K is still safe.

BTW, your OEM has designed it that way, and while they are squeezing the fat out of the margins, they are still largely going to fall on the safe side of things.