UOA Results vs. Oil Capacity

[blackdiamond]

I was just looking at a UOA for the 5.7L Toyota V8 and noted that the oil capacity was nearly 8 quarts (my 4.7L Toyota V8 was about 7 quarts) and was wondering to myself how much the oil capacity would "change" the UOA results.

As an example, consider a motor that produces exactly x amount of iron wear in a 5,000 mile period. The oil capacity is 8 quarts so in theory a single quart oil sample would contain 1/8th of the wear particles. If the engine were modified to only have a 4 quart capacity, the same single quart oil sample would have twice the wear particles and the UOA would look significantly worse.

If my memory serves me correctly, a lot of domestic engines have significantly small oil capacities compared to some foreign engines. I had several people ask what I was purchasing oil for when I carried 7-8 quarts out of the store. Wouldn't it be expected for Toyota V8 UOAs to look better than a GM UOA assuming the capacity's were different?

 

[Dad2leia]

The catch with that formula is that there are also some import engines that have a lesser capacity than their domestic counterparts. Honda for example, both the 2.4L I-4 in the CR-V and the 3.5L V-6 in the Pilot, haved approximately a 5 quart capacity (yes, I know the owners manual states differently, but I measure!). So, theoretically, even though its a 4 cylinder vs. a 6 cylinder, the 6 would show more wear even taking into account the additional 2 cylinders, and also taking into account that for the most part, Honda engines are very easy on oil and generally show little wear in the UOA's.

I would like to have a quart or two more in our Pilot, but I have to deal with what they gave me.

But I do like the premis of your discussion, and it does seem to make a grat deal of sense, but again, it's all engine design dependant and just how hard it is on the lubricant in the first place. That Audi engine that is discussed with the RLI lubes is a perfect example of just how hard they can be, and it has a 10 quart sump IIRC.

 

[[RT] ProjUltraZ]

i wish my LT1 350 had more than 5 qts, 315 hp/350 lbs torque and 5qts

another thing is ppm is measured as mg/Kg so X amount of metals in 5qts is going to give a higher conc sample than same amount in 7 qts. so the #s will be lower but same mass of metals worn off

 

[Punkey71]

My 2006 Hemi 5.7 has a 7 quart sump (the Mazda is 4.25). When I change with a 30 minute drain I can only get about 6.5 in. I'm switching to a longer Wix filter next time. I'm hoping to eek in 7.5 quarts....we'll see....

My hope is to get 10K OCI's on both of the cars in my sig. They see between 15-18K/year.

Currently at 5500 miles with standard size Wix and waiting till 8500 to change/UOA my ASM in the Charger ... the 8500 will put me at an even 20,000 miles for easier OCI tracking. I'll post it within a couple months as she sees about 1500 miles/month.

 

[blackdiamond]

I realize that not all foreign cars have higher oil capacity, but it sort of makes UOA results even more like apples and oranges than they already are.

My Mazdaspeed 3 has a 6 quart capacity and still shows high wear numbers.

It might be interesting to have people start posting oil capacity along with their UOAs for additional data to pretend to understand.

 

[deven]

Bigger engines have a higher surface area than smaller engines so in the end it evens out. A great question though.

 

[Master ACiD]

perhaps one should divide the ppm of wear metals by the quart capacity. for example, a honda b20b like my crv gets a uoa done that shows 12ppm of iron. this engine has a 4 quart sump, so 4 into 12 is 3ppm per quart.

my f150 has a uoa and shows 12ppm of iron, but its got a 6 quart sump. 6 into 12 means it shows 2ppm of iron per quart.

the honda would have higher iron than the f150 per quart.

perhaps theres even a way to take into account the number of cylinders and the mileage on the oil. maybe throw something in to differentiate between a filter change and no filter change. wonder how far someone could go with this.
then again, maybe ive got this all wrong.

 

[[RT] ProjUltraZ]

right, the labs probably take the total capacity into account

 

[Gary Allan]

Many indicators don't appear to track mileage ..at least directly. Fe appears to do so, but others don't. I don't know if I said that right. It may be nothing more than Fe being constantly shed in the reciprocating process as violations of boundary layer protection get breached. If they don't track mileage, it would also reason that they don't necessarily subscribe to dispersing/dilution norms either.

I'd say that it really doesn't matter as long as you compare to UA and that you're trending. Sure, we can always say that less is better ..but beyond that you're getting into fog.

 

[blackdiamond]

I would argue that mileage and dilution are very different factors with a UOA. It is just one more factor that makes comparing different engines more difficult.

I'm considering putting a larger oil pan on the Mazda that hold 1000 quarts because the solution to polution is dilution.

 

[Lonnie]

In severe service with light duty pickups we found that increasing the sump capacity is the single best thing you can do for the engine. Xtra time to warm up has proven to be a non factor. We have some V8's running with 9 to 12 quart sumps with nothing but positive results.

 

[blackdiamond]

I'm sure it benefits the engine, but wear in ppm would be expected to look reduced with increased oil capacity. How were your results documented?

 

[Lonnie]

As I have posted before we have some light duty pickups that service micro-wave stations in the desert and mountains where there are not paved access roads. Over 20 years or so we have done lots of stuff to harden these trucks with skid plates winches, great big air filters, bypass filtration but the single best thing has been to add a great big oil sump. In uoa's, even if you consider the dilution factor, all wear metrics were reduced and the engines lasted longer and had less difficulty passing Calif smog as they got beyond two or three year old. Spark plugs lasted longer and the engines that were torn down for inspection showed less overall wear. We spent some effort to make the engines last longer because we invest a lot in these trucks to put them into service. I can't tell you all the benefits that larger sumps give you but our last 4 trucks put into service received 12 quart sumps with windage trays and trap doors to keep the oil away from the crank when driving off road. We change the oil based on gallons of fuel burned and TBN. Mileage makes no sense in these conditions and the oil change per fuel used is being extended to other vehicles as well.

I'll give you an example of the large sump stuff. We have three older 4Runners with 4-cylinder engines in a deliver service where the drivers get paid by the trip and miles driven. These are like a pickup with a permanent camper shell. The deliver drivers have some kind of certification to be responsible for the stuff, like an armored car without the armor or shot gun. These vehicles are equipped with a tracking device and other stuff and cost a bit to configure for the job. One had an 8 quart sump installed. At the end of their life cycle the special stuff is being stripped out to be installed in new vehicles. The 4Runner with the big sump was torn down along with one of the other 4Runners. These vehicles must be scrapped, not resold so we had a chance to tear them apart. The difference between the two engines was pretty dramatic. That larger sump made a big difference in most of the wear parts inside the engine. I think that a larger sump might be a consideration in any engine that you would like help out a bit. It probably has no place in most application because of the cost and the fact that most engines do not work very hard for a living. We are using larger sumps only where it makes sense but in those cases a larger sump works well.

 

[Dad2leia]

Lonnie, I'm curious as to why you selected 4Runners with the 4 cylinder as opposed to the V-6, unless it's an ease of maintenance issue, or that you really didn't need the extra that the V-6 offered.

On the sump note, I would be super happy with an 8 quart sump (that would give me three extra quarts) and I would have no problem always going to the OLM extreme with the extra oil available for doing its job.

Driving on your job sounds like an adventure in fun and frustration!!!

 

[Lonnie]

The 4-cylinder is a better engine in every way except max horsepower. In tough stop and go driving we have had problems with the V6 of that vintage, head gaskets and water pumps. The new 4.0 V6 in the newer 4Runners is a much better engine but in this case for durability nothing beats the 4.7 V8. It's the most bomb proof engine we have ever dealt with.