Mixing oil - what is the purpose and how to measure effectiveness?

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Your over thinking this way to much. That engine will be fine from a redline 20wt. All the way up to a Motorex 10w-50. Simply use common sense on how u plan on using said equipment & pour 🛢 accordingly
 
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My dad has put 325 hours on a engine not supposed to make it too 275 hrs. Runs like the day it was brand new. He has used everything from monograde Tug Boat motor oil, to Motorex 10w-50, to supertech 10w-30. Only thing he's had to do is Tyres,suspension, filters, Clutch plates. 6,300 miles/325 hours.
 
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California. I think the colder I've seen where I live was in the 40F.



A specific oil was used for the break-in (SAE 30). The blend is for everyday usage moving forward. The engine was built to be dual purpose (road & track) with reliability as the main goal. I haven't had a chance to talk with the builder yet about what kind of oil he recommends on the track.




So my understanding without going into specific numbers is that the goal would be to have a thicker oil than regular 0/5/10W40 and thinner than 15/50? Is there a gap in between that isn't filled by other specialty oil on the market?



I called Driven Racing Oil the other day out of curiosity. Based on the clearances I gave them, they recommended running their 5W40.
You do realize Outlaw Race cars, running pure Alcohol(fuel dilution) don't even use 15w-50.
 

OVERKILL

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You do realize Outlaw Race cars, running pure Alcohol(fuel dilution) don't even use 15w-50.
That's not really relevant. GM has required 15w-50 for the Corvette for track use, Ford spec'd 5w-50 for the Track Pack version of the Coyote as well as the Ford GT, BMW spec'd 10w-60 for many of their M engines for years, and Ferrari also spec's 10w-60.

Since the OP is running an LS7 (Corvette engine) the range of viscosities being explored seems appropriate with the builder basically spec'ing an xW-40 at the heavier end of the spectrum.
 
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That's not really relevant. GM has required 15w-50 for the Corvette for track use, Ford spec'd 5w-50 for the Track Pack version of the Coyote as well as the Ford GT, BMW spec'd 10w-60 for many of their M engines for years, and Ferrari also spec's 10w-60.

Since the OP is running an LS7 (Corvette engine) the range of viscosities being explored seems appropriate with the builder basically spec'ing an xW-40 at the heavier end of the spectrum.
A 10w-60 is irrelevant 😴 pure marketing, just like Dad's Motorex 10w-50. Right now, I got him using SAE 40 Tug Boat motor oil in the crankcase & he don't even know it.😈☠ 2019 KTM 500 Exc-f 6,000 miles/ 325 hrs. He would freak if he knew 😈
 

OVERKILL

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A 10w-60 is irrelevant 😴 pure marketing, just like Dad's Motorex 10w-50. Right now, I got him using SAE 40 Tug Boat motor oil in the crankcase & he don't even know it.😈☠ 2019 KTM 500 Exc-f 6,000 miles/ 325 hrs. He would freak if he knew 😈
Not really, it's a factory spec'd visc for several engines and its development and use have an extensive history. This is similar to the Corvette program using M1 15w-50, there's a lot of history there.

We are of course talking about an LS7 Corvette engine in this thread, not a KTM bike, my reason for bringing up Ford and BMW is that they are also producing automotive engines where they spec heavier viscs for certain performance variants of their engines where track use is likely.
 
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Not really, it's a factory spec'd visc for several engines and its development and use have an extensive history. This is similar to the Corvette program using M1 15w-50, there's a lot of history there.

We are of course talking about an LS7 Corvette engine in this thread, not a KTM bike, my reason for bringing up Ford and BMW is that they are also producing automotive engines where they spec heavier viscs for certain performance variants of their engines where track use is likely.
Well said. One of my favorite members. Never negativity, just logical, useful information. Thank you for that OVERKILL.
 

OVERKILL

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I always wonder why the concern of mixing oils.
As has been explained several times, oils are blended, and tested, to meet a variety of performance targets, many of which have formal approvals. The chemistry of a mix is not validated in that manner and may produce undesirable results in terms of performance in certain areas.

To expand on this a bit further:
Base oil blend is chosen to meet both the performance targets for in service use (oxidation resistance, volatility, cold temperature performance) as well as the intended Winter rating. There's a compromise here because some of the performance targets may require more expensive base oil blends for a given winter rating. If we look at most of the Euro 0w-40's, they include PAO in the base oil blend for that reason, not because the blender wanted to go through the hassle of dealing with PAO, but because PAO brings with it some necessary characteristics to allow the product to meet those targets.

Additive chemistry is chosen in a similar manner. Many of the additive packages are "cookie cutter" against a suite of approvals, particularly those used by companies that aren't vertically integrated like XOM or SOPUS. These additive chemistries are intended for use in a specific slate of base oils (that's how they were tested and approved) and are of course a complex blend of AW, AF, elastomer compatibility...etc.

VII selection is made in a similar way. A North American GF-6/SP Resource Conserving oil isn't going to use the same type of VII's or treat rate as an extended drain Euro lube with a strict stay-in-grade requirement.

All of these parameters come together to dictate the "building blocks" of a fully formulated lubricant and compromises are made in some areas, or specific choices for materials are made, in order for the product to "check all the boxes" so to speak.

So, you mix together two oils and you have now upset that chemistry and of course the resultant mix has no formal approvals now and no testing to validate its performance. If you mix oils with very different chemistries, obviously this increases the likelihood that synergies that were present in the virgin products may be negatively impacted. One of the things that is most often impacted is the Winter rating, but that's often not overly relevant unless you live where it gets really cold like Winnipeg.

While oils are required to be miscible (the miscibility standard) that basically just means, as @Shannow pointed out numerous times in the past, that the resultant product isn't going to split like mayonnaise. It is in no way an endorsement for mixing, or a guarantee of performance for the resultant product.
 
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No you can't. You just made up two grades that don't exist in J300:


The oil, at 50/50, would have the following characteristics:
KV40: 93.58cSt
KV100: 15.19cSt
VI: 172

That makes it an xW-40, likely a 10w-40, though it may squeak in as a 5w-40.

Also, playing home chemist without any lab equipment means you have no idea what characteristics of the lubricant you've now compromised over each of the fully formulated products on their own.
We all know there is no such thing as a 7.5w-45 oil. I stated the mix would result in something like a 7.5w-45 (if it did exist) and is only a way to compare.

Say what you want about my methods but my vehicles' engines speak otherwise. They all run better than brand new.
 

OVERKILL

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We all know there is no such thing as a 7.5w-45 oil. I stated the mix would result in something like a 7.5w-45 (if it did exist) and is only a way to compare.
No, that's just silly. There are oils with the proper grading designation all over that spectrum. As I noted, Mobil 1 High Mileage 10w-40 is right at that viscosity (15.3cSt). These are RANGES, so trying to conjur up some fantasy "in-between" grade doesn't make sense, nor does it help the OP understand the system that assigns them. It also doesn't address the problem that the Winter rating doesn't just scale like KV100/KV40. That's why I posted J300, actually did the math, and then showed him an existing product that's right at the visc target his builder was shooting for.
Say what you want about my methods but my vehicles' engines speak otherwise. They all run better than brand new.
Engines, generally, are incredibly tolerant of a wide range of viscosities. Approvals set a floor for acceptable performance in many important areas, none of those are anecdotal about "running better than new" but based on actual wear performance, deposit prevention, oxidation resistance...etc. Scientifically defined and validated parameters.

A preponderance of proof in this scenario would be a series of controlled operating runs of both OE spec and your "home brew" changed at the same intervals, run up to a certain number of hours and then tear-down analysis performed to qualify and quantify performance. That's the method in which Porsche validates their oil approvals, using simulated lapping of the Nurburgring on an active dynometer. This is the level of rigour required.
 

herwawan

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This thread is a wealth of information, thank you all for contributing!

At this point, a couple of elements are pretty clear:
- mixing oil is fine on paper, although, without a proper rigorous testing methodology, there's no way to know if it does provide any benefit over using one specific oil
- the "mix" of these two oils create a blend close to the Mobil 1 High Mileage 10w-40 in terms of KV40/100

MIX 50% 0w-40 / 50% 15w-50
Mobil 1 High Mileage 10w-40
Mobil 1 FS X2 5w-50
KV40
93.58​
101​
104.3​
KV100
15.19​
15.3​
17.1​
VI
172​
179​

One thing that's interesting is some of you mentioned going with a 5w-50. With that oil though, we're further from the mix as calculated by @OVERKILL as shown above (I couldn't find the VI for the 10w-40).
 

OVERKILL

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This thread is a wealth of information, thank you all for contributing!

At this point, a couple of elements are pretty clear:
- mixing oil is fine on paper, although, without a proper rigorous testing methodology, there's no way to know if it does provide any benefit over using one specific oil
- the "mix" of these two oils create a blend close to the Mobil 1 High Mileage 10w-40 in terms of KV40/100

MIX 50% 0w-40 / 50% 15w-50
Mobil 1 High Mileage 10w-40
Mobil 1 FS X2 5w-50
KV40
93.58​
101​
104.3​
KV100
15.19​
15.3​
17.1​
VI
172​
179​

One thing that's interesting is some of you mentioned going with a 5w-50. With that oil though, we're further from the mix as calculated by @OVERKILL as shown above (I couldn't find the VI for the 10w-40).
VI of the HM 10w-40 is 160 (VI is just a calculated value based on KV100 and KV40).
 

ZeeOSix

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This thread is a wealth of information, thank you all for contributing!

At this point, a couple of elements are pretty clear:
- mixing oil is fine on paper, although, without a proper rigorous testing methodology, there's no way to know if it does provide any benefit over using one specific oil
- the "mix" of these two oils create a blend close to the Mobil 1 High Mileage 10w-40 in terms of KV40/100

MIX 50% 0w-40 / 50% 15w-50
Mobil 1 High Mileage 10w-40
Mobil 1 FS X2 5w-50
KV40
93.58​
101​
104.3​
KV100
15.19​
15.3​
17.1​
VI
172​
179​

One thing that's interesting is some of you mentioned going with a 5w-50. With that oil though, we're further from the mix as calculated by @OVERKILL as shown above (I couldn't find the VI for the 10w-40).
Since the 50/50 mix and the Mobil 1 10W-40 KV100 viscosity is basically the same, I'd just run the 10W-40 since you're in CA and don't have to worry about super cold start-ups. Why complicate it by mixing oils.
 
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That's not really relevant. GM has required 15w-50 for the Corvette for track use, Ford spec'd 5w-50 for the Track Pack version of the Coyote as well as the Ford GT, BMW spec'd 10w-60 for many of their M engines for years, and Ferrari also spec's 10w-60.

Since the OP is running an LS7 (Corvette engine) the range of viscosities being explored seems appropriate with the builder basically spec'ing an xW-40 at the heavier end of the spectrum.
if op just ran a regular xw-40 or a 50w, dont think the cst is that big of a difference.
 
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