Engine Size - How Hard Does Oil Work?

[FloatingBrick]

Does the oil in my 5.8 work harder than the oil in my wife's 3.0? My common sense tells me that, with both engines having a 5 quart capacity, the oil in the smaller engine does not have to cool, lubricate, and clean as much surface area per cycle (pan - pumped through engine - back to pan). Am I thinking about this correctly?

If oil works harder in larger engines, should OCIs be shorter?

 

[MGregoir]

I think it could really depend on things. Look at the specific output of the engine.

A 200 cubic inch engine that makes 200 horsepower with a five quart oil capacity versus a 350 cubic inch engine that makes 250 horsepower with a five quart capacity will probably generate higher bulk oil temperatures, have higher compression and more blowby potential, operate at higher rpm, etc.

That "big" 350 will not have to work as hard to make as much power, and although the oil has to cover more area and more equipment, it may not face as many stresses.

 

[MolaKule]

The type and capacity of oil cooling and filtering that is available also affects the oil's rate of degradation. If the larger engine has a higher cooling capacity, then your theory may not hold.

Oil analysis with trending and expert used oil analysis is the only way to determine how much the oil is degrading.

Another factor is that some engines shear the oil more than others.

So these are just a few of the many factors regarding the rate of oil degradation and required oil change intervals.

 

[dwendt44]

The smaller engine will likely rev higher on many occasions as well. It all adds into the mix.

 

[FZ1]

I would think that the greater the explosions in the cylinders, the greater the contaminates with which the oil must deal. Love those huge BMW sumps.

 

[artificialist]

I figure the engine that produces the most pollution of the two would be the hardest on oil.

The engine built to the lowest tolerances would be the hardest on oil.

Whether or not the engine uses roller lifters/followers or not could be important.

I also figure the one with the most moving parts would be the hardest.

 

[jorton]

I've heard vw and audi engines are hard on oil, and I've heard towing/hauling heavy loads is hard on v8's in trucks. So if her car isn't a vw or audi and if you don't tow/haul, I think both cars can use a normal oci.

If either car's oil has serious fuel dilution, it(they) should be on severe service oc schedule.

 

[Gary Allan]

Quote:
So if her car isn't a vw or audi and if you don't tow/haul, I think both cars can use a normal oci.


I don't know if I'd just limit it to those conditions/qualifiers ..but they're good ones to determine severe conditions. Not all VW/Audi have issues ..but most do have fancy requirements for spec'd OEM OCI service lengths.

All the elements mentioned (by everyone) sorta index themselves on the "oil insult quotient". Some engines are buffered better than others so they can share a like sump volume and have radically different displacements without compromise.

 

[mechtech2]

The weight of the respective vehicles [thus the load imposed], and the efficiency of the cooling systems seem to be the keys.
It could go either way.

 

[artificialist]

Many VW and Audi engines use turbochargers which raise engine pressure significantly, and also raises oil temperature. Certain VW and Audi engines have direct gasoline injection, which has been shown to dilute the oil with fuel more than multi port fuel injection.

That in mind, VW has some very specific oil requirements to deal with this. I sure have seen many problems where the owner doesn't at least use synthetic.

 

[OVERKILL]

Is the engine a 351W?

 

[Chris71]

I am no expert but I would think that smaller engines rev higher and thus would be harder on oil.

 

[Max_Wander]

i'd just roughly calculate power output / cylinders , higher value indicating higher stresses

 

[Dale_Knight]

Would installing custom made larger sumps help us sump size deficient folk keep the oil in better condition to achieve extended OCI's or keep our engines running with relatively cleaner and cooler oil?

 

[Black_Thunder]

also depends on what each vehicle is used for.


certainly you aren't pulling a camper with your wife's vehicle equipped with a 3.0

 

[steve20]

the engine which uses the most fuel/mile will be the one working the hardest consequently this engine will be the toughest on oil. How's that for a definitive answer?

 

[bob_ninja]

Actually the driver is far more significant factor than engine size. For instance, when I relax in the right lane at 55mph, even though I only have a small 1.5L 3qt sump it may not work as hard as the bigger SUVs and vans passing me at higher speeds.

So given the same driving pattern and same vehicle body (weight, CD, tires, ...) smaller engine will work harder. However, in practice vehicles are very different. So bigger engines tend to be in bigger/heavier vehicles, higher CD and bigger higher friction tires. Combined with aggressive driving and you could easily have a 3L engine work harder than my 1.5L Honda.

 

[Gary Allan]

Quote:
That in mind, VW has some very specific oil requirements to deal with this. I sure have seen many problems where the owner doesn't at least use synthetic.


..but they spec a synthetic...

The problem children were when very few oils met VW/AUDI spec's and they were only available from the dealer (typically). It was a mad rush to make VW 500.xx- oils available. The OCI's were too long ..the sumps too small .and the needed oils too hard to find for Americans who don't have time to take their car to a dealer. For all we know the dealers didn't bother using the spec'd oil either.

Quote:
Many VW and Audi engines use turbochargers which raise engine pressure significantly, and also raises oil temperature.

Which is why most of them have heat exchangers and spec a synthetic with pretty specific qualifications. It does little good to follow half of the factory recommendations. That is, take advantage of the service interval while ignoring the specific oil requirement that it's enabled by.


Was the Ford Explore problem really a poor tire spec? ..or was it lame people on cellphones being too busy to check their tires like they should?? Does a 250lb rated ladder get the blame when you subject it to 400lbs?

 

[FloatingBrick]

Overh1ll - yes it's a 351w.

Both cars see very light mileage around town. The V8 has issues since it only goes about 15 miles round trip per work day - but no towing or heavy strain. The wife's Taurus gets a 30 mile workout 3 days a week and short trips on the weekend.

Haven't done a used oil analysis on the 3.0 (haven't had the car long enough), but the results for the 5.8 (after 3k) said it would be okay to go on out to 5k. Fuel dilution was a concern (carburated), but was unfounded. Both are in the middle of ArX wash treatments, so it will be next year before the 3.0 gets a used oil analysis.

Really, the question was just out of curiosity after looking at the 5.8 and then the 3.0 and thinking about the 5 quart sumps.

 

[OVERKILL]

Originally Posted By: FloatingBrick
Overh1ll - yes it's a 351w.

Both cars see very light mileage around town. The V8 has issues since it only goes about 15 miles round trip per work day - but no towing or heavy strain. The wife's Taurus gets a 30 mile workout 3 days a week and short trips on the weekend.

Haven't done a used oil analysis on the 3.0 (haven't had the car long enough), but the results for the 5.8 (after 3k) said it would be okay to go on out to 5k. Fuel dilution was a concern (carburated), but was unfounded. Both are in the middle of ArX wash treatments, so it will be next year before the 3.0 gets a used oil analysis.

Really, the question was just out of curiosity after looking at the 5.8 and then the 3.0 and thinking about the 5 quart sumps.



Old carbureted 351w? Slap some Delvac 1 5w40/Mobil 1 Turbo Diesel Truck 5w40 in it and drive with confidence. It's overkill, but hey, it's good oil