How much difference does oil really make?

[Nessism1]

While I can appreciate that some boutique oils use high grade base stock, that won't shear out of grade as fast as some cheaper oils, holding grade is only one requirement for engine oil. With DI engines that dilute their oil with fuel, stable viscosity oil is going to waste if you have to change it to remove fuel. And short trippers, what accumulate condensation in the oil should change every year regardless of low mileage.

No doubt, there are some good use cases for high mileage boutique oils, that doesn't mean they will benefit everyone.

 

[SC Maintenance]

It's not nearly so simple as "thick oil good, thin oil bad".

As much as I dislike YouTube videos, this guy does a great job explaining what GM was doing and why.

So a OEM that wants to run thin oil and a youtuber that wants clicks get together to tell me why film thickness doesn't matter.

Then as soon as the OEM has engine problems they spec a much higher weight oil, which they then need to rescind - most likely because they got a call from the CAFE folks.

Thats some drama there for sure.

 

[Nessism1]

So a OEM that wants to run thin oil and a youtuber that wants clicks get together to tell me why film thickness doesn't matter.

Then as soon as the OEM has engine problems they spec a much higher weight oil, which they then need to rescind - most likely because they got a call from the CAFE folks.

Thats some drama there for sure.

That's not how I interpreted that video. I thought it was very informative.

He showed how thick oil doesn't necessarily protect the engine better, and can cause extra drag. Basically, the oil needs enough film strength to eliminate metal to metal contact, and any extra viscosity above this point causes needless drag and provides no functional advantage.

 

[ltslimjim]

No doubt, there are some good use cases for high mileage boutique oils, that doesn't mean they will benefit everyone.

They also don’t hurt anything despite being less optimal purely from a marginal price difference. That’s pretty much the only actual knock on boutiques. Literally nothing to do with performance. You never hear it said “I’m using a cheaper oil because it performs better than the boutique oil“.

That’s why I find this all rather humorous. I don’t mind paying more for the best. It’s not a significant price difference. The approach of always get the cheapest as an important factor is just silly to me unless you need the upfront savings. Long term potential benefits. Minimum insurance coverage vs better protection, but for like $8 a month difference, in that sense it’s a no brainer to me.

.02

 

[Starving Electrician]

It's not nearly so simple as "thick oil good, thin oil bad".

As much as I dislike YouTube videos, this guy does a great job explaining what GM was doing and why.

Never said it was that simple only that everything else being equal same engine, same base oil, same additives (save for VII's of course), and proper quantity of oil then a thicker oil will protect better. That is just the hard truth of it. Now viscosity isnt the only factor but as far as the oil goes its the most important single factor.

Now I fully acknowledge thick enough is just that thick enough, but how do you guarantee it stays that way in ALL operating conditions? One simple way is to make the oil thicker than it has to be. You loose a bit of power and some efficiency but you gain wear protection.

Now again thick enough is thick enough thats also completely true. If your 0w-8 is always providing hydro dynamic lubrication then great its working, but what if it doesnt? What if it shears out of grade? All things that can happen and dont seem worth the risk to many like myself. Again guys that run thin oil aren't wrong any more than thickies are right. Just that each is making a choice and as long as it's an informed choice then it's a valid one.

 

[Nessism1]

They also don’t hurt anything despite being less optimal purely from a marginal price difference. That’s pretty much the only actual knock on boutiques. Literally nothing to do with performance. You never hear it said “I’m using a cheaper oil because it performs better than the boutique oil“.

That’s why I find this all rather humorous. I don’t mind paying more for the best. It’s not a significant price difference. The approach of always get the cheapest as an important factor is just silly to me unless you need the upfront savings. Long term potential benefits. Minimum insurance coverage vs better protection, but for like $8 a month difference, in that sense it’s a no brainer to me.

.02

How do you define "marginal price difference?" Apparently, differently than I do. I recently jumped on the Costco oil deal, at $15/5 quart jug. 3x that for boutique oil is not marginal to me. I'd rather spend the delta on beer.

 

[thetricky]

My argument is that the fancy oil does little to increase the probable life span of your typical car so long as you change it at a reasonable interval. The most likely outcome is that at some point either something non oil related will go bad that isn't economically feasible to repair or an accident that totals it.

Severe oil burning is not so prevalent as the echo chamber that is BITOG would have you think. I've owned many vehicles that reached over 200k and only one burned much oil and it did it from nearly new. What kills engines is overheating and neglect.

Did you fully read my post?

I will never claim that boutiques will extend a machines life with lower wear than OTC oils, Blackstone has shown us that there is statistically no difference across oils.

I am talking about staving off oil burning, which can cascade into other problems. Remember, you are a sample size of just one, sure you haven’t had oil burners, hell I haven’t either. We however, are not the millions of people who pull into a quick lube when the OLM tells them to and could care less what oil they get, as long as that vehicle takes them from a-b whenever they ask it to. That’s a recipe for oil burning. I have also noticed a lot of people don’t care about maintenance because they trade vehicles in so frequently, again, another situation creating oil burners. So yes, oil burning is an issue in the bigger picture. I follow people in on my commute everyday leaving a sweet blue trail.

 

[thetricky]

Easy most of these very expensive oils are great they stand up better to extreme conditions than other oils. Whether that's better HTHS longer drain intervals and the like. A commuter car that is driven moderately on the highway will never see those conditions. So the oil will do no better of a job protecting the engine.

Now the expensive oils probably make some people feel better which is subjective, but using a boutique oil in a commuter car is like using O2 safe Krytox grease in a paintball marker (gun if you aren't a player). Yes it’s a better grease yes it holds up in more extreme conditions, but those are conditions a paintball marker never experiences so why spend all that extra money.

My vehicles fall into the severe service category so boutiques are indeed a perfect fit for them, like you explained. Motorcycle is my commuter, 12 miles one way redline shifts, ridden hard, fuel dilution. Outback is grocery getter, some short trips. Truck hauls the boat and large other random loads in warm weather. All these use cases are good applications for boutiques.

 

[ltslimjim]

How do you define "marginal price difference?" Apparently, differently than I do. I recently jumped on the Costco oil deal, at $15/5 quart jug. 3x that for boutique oil is not marginal to me. I'd rather spend the delta on beer.

So obviously, a boutique is only less expensive than oil on sale, the more miles that are racked up in less time and therefore when you cross a certain threshold for OOP cost differences between the two oil choices and the accompanying maintenance approaches.

Still, even with more OOP you pay way more in fuel cost in a single week or month the more or less that is driven. Oil cost is usually just not meaningfully different. Again, as I said in my other post, this may be a problem for some budgets and I respect that.

 

[ltslimjim]

Maybe $200 in a year for boutique oil twice changed; at worst? Meanwhile minimum 2 changes on cheaper oil is $30 at the above rate. So, the cost difference is; at most, $14 a month? Not a big deal to me. That’s using a typical “changes more often than sometimes necessary” model.

In my vehicle, even with burning oil…it’s at $100 a year…vs $30 changes every 6 months (though let’s be real not always on sale for $15 twice a year unless buying cheapest possible)… either way that’s $70 or $40 more annually; and is not much more than a cup of coffee a month difference. Just under $6 a month or just over $3.

ADDED: Is that really much of a savings on money; just to save money, when I can get objectively a more robust oil? I’ve been there in the red and trying to save money or not having the cash flow. I just think the OOP short-term is way way overblown otherwise.

 

[ltslimjim]

I’ll add one more important point. Even if you change oil on a boutique as frequently as the cheapest oil off the shelf, in scenarios where oil breakdown may be accelerated; and thus requiring more frequent changes…then regardless, there is the issue of how clean the oil runs.

In such a severe service scenario, the boutique has way more headroom to prevent issue such as deposit formation, even if changed as frequently. Again, cheap insurance. A full tank of gas is basically already the same cost difference.

 

[SC Maintenance]

That's not how I interpreted that video. I thought it was very informative.

He showed how thick oil doesn't necessarily protect the engine better, and can cause extra drag. Basically, the oil needs enough film strength to eliminate metal to metal contact, and any extra viscosity above this point causes needless drag and provides no functional advantage.

This is all true, but who gets to decide what a thick enough film is? Thick enough under ideal conditions. Under what temperature. What happens if the oil shears more than expected. Who did the math - was it correct? What is there definition of acceptable wear?

In Engineering their is always a Factor of Safety - you design then you add a little. What is the FoS on these thinner oils? Likely application specific but its for sure less.

The Drag as you call it, is a true cost. Most OEM's it seems figure about 1.5% fuel savings going down a grade. So that is a real ROI - how much are you willing to pay to get that additional FoS. Everyone can do their own math. So really its not much different than the question of premium vs not premium oil, however in this case the numbers are far clearer, in my mind at least.

One thing was clear was that as soon as GM had bearing problems they immediately up-spec'd two viscosity levels. At least until the lawyers called. That is telling to me.

 

[4WD]

So a OEM that wants to run thin oil and a youtuber that wants clicks get together to tell me why film thickness doesn't matter.

Then as soon as the OEM has engine problems they spec a much higher weight oil, which they then need to rescind - most likely because they got a call from the CAFE folks.

Thats some drama there for sure.

I think we now know there were bearing clearance issues - some bad cranks from etc - which is why after a search - they changed 0W20 for 0W20 in my buddy’s Z-Bison … Then he drove it to the trails and pounded on the 6.2L …

 

[Nessism1]

One thing was clear was that as soon as GM had bearing problems they immediately up-spec'd two viscosity levels. At least until the lawyers called. That is telling to me.

How do you know it was the lawyers? Maybe on further review, GM high brass realized that the oil thing was a temporary band-aid on a bigger problem? That's what I think. And in my former career, I was involved in that sort of discussion.

 

[KevinMalone]

Something that really changed my perspective was talking maintenance with high mileage taxi owners. They use the cheapest stuff possible and continue to rack up >300k miles.

So yeah, unless a vehicle is track driven or has some other exception, Supertech or Kirkland synthetic will likely exceed the requirements of a normal street driven vehicle.

 

[SC Maintenance]

How do you know it was the lawyers? Maybe on further review, GM high brass realized that the oil thing was a temporary band-aid on a bigger problem? That's what I think. And in my former career, I was involved in that sort of discussion.

I am 100% confident it was a band aid. The point being that a thicker viscosity helped with a problem. So if it helps with a problem then in a non problem engine it would have a higher FoS.

The "proof" that gives me confidence is simply they issued the statement to change, then they un-issued it. I have worked with enough engineers to know they don't tell people to go do something the first time unless they have pretty good data that says they should. So something else changed there mind.

 

[Glenda W.]

This is from the GM engineer.

“Fenske goes on to explain that the recall calls for affected units to have their oil replaced with high-viscosity 0W-40 Mobil 1 Supercar oil rather than the 0W-20 oil originally specified upon passing an inspection. Then, he uses his automotive engineering expertise to explain why using a different oil viscosity is supposed to prevent the engine failure issue.

It’s all about an engineering concept called the Stribeck curve. The Stribeck curve is a way of measuring proper lubrication by charting the friction coefficient on the Y axis and the Hersey number on the X axis. There are three distinct regions on the curve: boundary lubrication (high-friction, metal-on-metal contact), mixed lubrication (some, but incomplete separation between metal parts), and hydrodynamic lubrication (metal parts are completely separated by a layer of oil. Naturally, reducing metal contact decreases friction, making the Stribeck curve go down in the mixed lubrication phase.

The Hersey number measured on the X-axis is a formula that measures lubricant viscosity multiplied by sliding speed divided by load pressure. GM’s goal in using a thicker oil in the L87 engine is an effort to increase the Hersey number so the engine spends more time in the hydrodynamic lubrication phase of the Stribeck curve.

Fenske further explains why GM is making the switch from 0W-20 to 0W-40. Generally speaking, it’s inadvisable to increase the first number or decrease the second number in an engine oil’s viscosity, because it introduces the engine to a viscosity it isn’t designed for. However, increasing the second number isn’t as risky since the whole operating range of 0W-40 oil is within the operating range of 0W-20 oil.”

 

[rstcso]

I think of oil in the same manner as duty/type ratings of ladders. You can buy the least expensive Group I oil and it will pour into your engine, if you want. Most likely, somewhere in the middle, is the manufacturer's recommended oil based on viscosity, API or other ratings/approvals. Then you have boutique oils, realizing not all are created equal, <blah-blah-blah> (insert your arguments here).

If you, and what you're carrying up a ladder, don't exceed the rating, the ladder should support you, allowing the job to be done (shakiness aside). My being old, overweight, and carrying some heavy tools, I'm going to err on the side of caution and use a Type IA, although based on my specs, I could use a Type I. The potential downside is the Type IA is going to weigh more, so it increases my workload (0w-20 vs 5w-30, however minuscule potential fuel gain/loss).

Let the analogy policing commence!

 

[Patman]

Something that really changed my perspective was talking maintenance with high mileage taxi owners. They use the cheapest stuff possible and continue to rack up >300k miles.

So yeah, unless a vehicle is track driven or has some other exception, Supertech or Kirkland synthetic will likely exceed the requirements of a normal street driven vehicle.

That’s not even close to the type of conditions that the average engine will see though, so their results are pretty much irrelevant

 

[Panda87]

That’s not even close to the type of conditions that the average engine will see though, so their results are pretty much irrelevant

That was my thinking. Now if they were trucks and towing campers 24/7, this would be a different story