Does a smaller sump really matter?

[zach1900]

Another poster was just talking about his 155K mile 2006 Sentra, I owned a 2001 version, same generation, engine , transmission etc (1.8L 4cyl), mine barely held 3 quarts of oil (in fact I think it called for 2.7 qts.) and had what a BITOGE'R would call a thimble of an oil filter, well I drove that thing for 160,000 miles in addition to the 90K miles that it had when I bought it , when I traded it in at 250,000 miles it was still going strong and mind you I was very lax on oil changes, dino or at best Castrol syn blend every 10,000 miles, heck I even drove it for a year with a seeping radiator.
What is this obsession with trying to increase what the sump holds by going against manufacture recommended oil filter sizes and such, only so much oil can actually be in the engine at any given time, right? I mean what's the point of a huge oil pan if only a small fraction of that oil is actually in the engine, to the folks that mention getting the engine up to temp ASAP, wouldn't just enough oil warm up faster than excess oil ? **rant over**.. Thoughts?

 

[eljefino]

The fieros with 2.5 iron dukes had a special, shallow oil pan so the motor would fit in the car.

So they were always a quart low anyway. Burn a little oil and you overheat and get a car fire.

I respect GM for squeezing 5 quarts in their econoboxes. That's the most you can get out of a quicky lube without paying extra, and they factor the additives holding out into their OLM, I'm sure.

 

[donnyj08]

I think the manufactures are doing it so they can offer 10k mile oil changes on the thinner fuel efficient oils while still allowing enough additive protection for a full 10k miles without warranty claims.

Its all about getting longer more friendly service intervals, better MPG, and long engine life

 

[zach1900]

Good thoughts, maybe modern oil are even better (dino included) than we give them credit for.

 

[901Memphis]

An increase in oil capacity should correlate directly with a longer oci capability if everything is mechanically sound. Increase a sump from 3 to 4 quarts and you have another 25% the oil should last longer TBN wise.

Also more oil is more fluid to hold heat if the application involves racing.

It's a cheap hobby

 

[userfriendly]

Size matters.

 

[Shannow]

The piston/rings is where the majority of the oil degradation is taking place, so the less frequently the oil is in that area, the longer it's life.

So for a given engine, 20% more sump volume means 20% less trips to the ring belt.

 

[Nick1994]

Good thing I overfill my Camry, it takes 3.8 quarts and I always put in 4

 

[Justin251]

The only thing keeping me from the 7500 mile oci in my hyundai is that it only takes 3.5 quarts.

After 6k miles I'm changing. It's cheap enough.

 

[donnyj08]

Originally Posted By: Justin251
The only thing keeping me from the 7500 mile oci in my hyundai is that it only takes 3.5 quarts.

After 6k miles I'm changing. It's cheap enough.



Im with you there. 3.5qts is not much to do extended OCI's.

 

[turtlevette]

If it were my car, I'd want the largest amount of oil possible. Cooling is also a consideration. Some here say no but the majority of stuff you find on car sites says more oil helps cooling.

 

[Shannow]

turtlevette, the suface area exposed to the wind doesn't change...and it would take seconds for the extra quart to pick up in tmerpeature anyway.

by "majority of car sites" are you saying that you are representing "other people's work" ???

 

[Justin251]

Originally Posted By: donnyj08
Originally Posted By: Justin251
The only thing keeping me from the 7500 mile oci in my hyundai is that it only takes 3.5 quarts.

After 6k miles I'm changing. It's cheap enough.



Im with you there. 3.5qts is not much to do extended OCI's.


The manual recommends quaker state (doesn't specify aside from that) in 5w20,5w30,or 10w30 for 7500 miles.

Nope!

 

[dishdude]

A larger sump give you a more robust oiling system. Longer ocis, more forgiving on being run a quart or two low.

 

[turtlevette]

Originally Posted By: Shannow
turtlevette, the suface area exposed to the wind doesn't change...and it would take seconds for the extra quart to pick up in tmerpeature anyway.

by "majority of car sites" are you saying that you are representing "other people's work" ???


Well put it this way , most car enthusiasts side with me on this. You just admitted in a post above the oil spends xx less time in the ring area. Xx less time in bearings. And xx more time in the sump cooling.

I don't know how someone can argue against something so obvious.

 

[Shannow]

As you well know, what seems obvious and intuitive, particularly to a layperson is generally wrong in an engineering sense.

There's nothing about "time" in the sump in the equation...heat transfer is temperature dependent.

At steady state, e.g. at the end of the straight, it doesn't matter how much oil is IN the sump, it will be shedding heat to the environment at the same rate...dependent entirely on the temperature, not the time that it's there.

Say that the viscous friction at 5,000RPM is 5 KW, and even give the "raging fire" above the pistons as another 5KW...a 5 quart sump will heat at 1.25C per second, a 6 quart sump will heat at 1C per second, hardly enough to write home about.

The temperature in both cases will rise until it's hot enough to shift that heat to the environment...But the heat transfer to the environment will equalise at whatever it does, and they'll be exactly the same temperature, literally within seconds of each other.

 

[Shannow]

BTW, you discredit nearly everything I bring to discussions but are hanging your hat on motor rags and "everyone else" ?

That's some bibliography.

 

[SumpChump]

Originally Posted By: Shannow
BTW, you discredit nearly everything I bring to discussions but are hanging your hat on motor rags and "everyone else" ?

That's some bibliography.


Shannow, you know your stuff. Thanks for being on BITOG.

To get your opinion... If an adtermarket sump came out for your car that held 2-3 more quarts.... Would you bother?

 

[CourierDriver]

My old, now gone, but not forgotten 67 VW Beetle, 1500cc engine, no oil filter, almost 3 quarts of oil,,,ran forever, no worries and that was ancient technology....so why do cars today need oil filters.....

 

[Shannow]

Depends how and why thy made it bigger.

If it was just an inch wide strip of sheet to drop the bottom of the pan like some used to do on the SBCs, then no, I wouldn't bother.

If it was a larger plan view that kept more oil between fill and full and I was planning a cannonball run, I would.

If it was to have "wings" to hold more oil and provide cooling I'd consider the application.

e.g. back in the 1970s, Ford were about to release the Phase 4 GTHO Falcon...the Phase 3 was 140MPH 4 door family car...in 1970...the Phase 4 was to be the killer blow at Bathurst.

They were going to have a pretty wild 351 Cleveland, and the sump that was to be in it made itself (and the engines did too) to a bunch of Fairlanes after the Govt stopped the project. Sump looked like th following pic...

It clearly held more oil, clearly had more surface area, but I think was designed by "feel" rather than designed...I seriously doubt that it did much.

Here's what Holden did with the V-6s in Oz
https://bobistheoilguy.com/forums/ubbthreads.php/topics/3692871/What_we_Holden_doing_-_sump_de

They needed the volume, as Aussies weren't used to running out of oil in 6,000 mile service intervals.

But even still, the oil in the dipstick region is 110C after a 25km commute.

I guess it boils down to I wouldn't bother.