# What's the viscosity of this franken-brew?

#### cwilliamsws6

I have this jug of franken-brew in my garage I've been waiting to use but I'm curious as to what the final viscosity of it roughly equals out to. It consists of the following:

2 quarts 10w40
1 quart 10w30
1 quart 5w30
1 quart 0w40

Roughly what viscosity will this mix out to be?

#### JohnnyJohnson

Well I see you live in Idaho, so you do get some cooler weather. But in my mind what I would say about that viscosity = Good enough!

#### cwilliamsws6

Well I see you live in Idaho, so you do get some cooler weather. But in my mind what I would say about that viscosity = Good enough!
Fair enough, I was going to wait and run it in the summer if it makes any difference.

#### Imp4

I have this jug of franken-brew in my garage I've been waiting to use but I'm curious as to what the final viscosity of it roughly equals out to. It consists of the following:

2 quarts 10w40
1 quart 10w30
1 quart 5w30
1 quart 0w40

Roughly what viscosity will this mix out to be?
Without knowing the performance specs of each quart of oil, there is not enough information provided to determine a valid answer.

SAE J300 & ASTM D445 define viscosity grades and provide the range of kinematic viscosities that define each grade. Manufacturers are then free to label their products appropriately as long as the product falls within the defined range.
Without the kinematic viscosities for each quart of oil you possess, it is just a guess as to what the result will be.

Here is a handy chart for your reference.

Last edited:

#### tblt44

I have this jug of franken-brew in my garage I've been waiting to use but I'm curious as

7w36

10W40

#### SR5

+1
You beat me to it

#### SR5

Without taking it to a lab and measuring it correctly, this is probably the best guess, a thinish 10W40.

The straight average gives 7W36, but with oil grades your in or out.
So if it can't make 5Winter for low temp starting, then it's 10Winter (10W). If it's above a 30grade in viscosity, then it's a 40grade.

OP, what brands?

#### cwilliamsws6

Without taking it to a lab and measuring it correctly, this is probably the best guess, a thinish 10W40.

The straight average gives 7W36, but with oil grades your in or out.
So if it can't make 5Winter for low temp starting, then it's 10Winter (10W). If it's above a 30grade in viscosity, then it's a 40grade.

OP, what brands?
2 quarts autozone 10w40
1 quart Shell 10w30
1 quart Mobil One 0w40
1 quart Pennzoil HM 5w30.

Not sure of the API rating on them but I know they are all from within the last 10-15 years so not suuuper outdated at least.

SR5

#### Kuato

I have this jug of franken-brew in my garage I've been waiting to use but I'm curious as to what the final viscosity of it roughly equals out to. It consists of the following:

2 quarts 10w40
1 quart 10w30
1 quart 5w30
1 quart 0w40

Roughly what viscosity will this mix out to be?
It will act approximately as a 30 weight oil, but you cannot count on cold-weather performance lower than a 10W.

A few months ago, I submitted a sample and had it tested… It was an even mix of 5W-20 and 20W-50 which came back as a heavy 30 or a light 40 grade.

#### cwilliamsws6

It will act approximately as a 30 weight oil, but you cannot count on cold-weather performance lower than a 10W.

A few months ago, I submitted a sample and had it tested… It was an even mix of 5W-20 and 20W-50 which came back as a heavy 30 or a light 40 grade.
That's actually quite fascinating. I'll probably run it for my summer OCI and see how it does.

#### kschachn

2 quarts autozone 10w40
1 quart Shell 10w30
1 quart Mobil One 0w40
1 quart Pennzoil HM 5w30.

Not sure of the API rating on them but I know they are all from within the last 10-15 years so not suuuper outdated at least.
But regardless of whatever the grade (viscosity) happens to be with that mixture, there is zero guarantee that it meets any license, specification nor approval that any of the individual oils may have carried. That would be more concerning to me than whatever grade it makes.

#### Kuato

But regardless of whatever the grade (viscosity) happens to be with that mixture, there is zero guarantee that it meets any license, specification nor approval that any of the individual oils may have carried. That would be more concerning to me than whatever grade it makes.
Yeah mixing brands and additive packages = unknown composition. Ok for a 5k run though IMO.

That's actually quite fascinating. I'll probably run it for my summer OCI and see how it does.
I thought so too. Will be combining some Schaeffer 5w-20 , 20w-50 and 15w-40 for next summer...and not worrying one bit.