Blending Numbers: M1 0w20 and 0w40, VOA

[BigJohn]

I have a simple question, that I suspect has a complex answer.

If I mix 4 quarts of M1 0w20 with 5 quarts of M1 0w40, what are the numbers?

If it is simple math (which I doubt it will be that simple), it would be the following....

Oil Weight

4 x 20 = 80, 5 x 40 = 200, 80 + 200 = 280, 280 / 9 = 31.1

So, is this blend and .... 0w31 ....?


Similarly, what about HTHS?

4 x 2.7 = 10.8, 5 x 3.8 = 19, 10.8 + 19 = 29.8, 29.8 / 9 = 3.31

Does this blend have a HTHS of 3.31?


Then there is Viscosity Index.....

4 x 173 = 692, 5 x 185 = 925, 692 + 925 = 1,617, 1,617 / 9 = 179.7

Does this blend have a Viscosity Index of ....basically 180?


If simple math is the answer..... then this blend seems to be pretty awesome for a 30wt oil.

Weight = 0W31
HTHS = 3.31
Viscosity Index = 180


Why may you ask, am I considering such a blend.....seems nice for my wife's Mercedes GLK for a winter solution, rather than straight M1 0w40. And....I can buy this solution really cheap at my local WalMart. (Yes, we have already had some negative 10 to negative 15 degree mornings this year here in Colorado.)

 

[dparm]

Yep, your math looks correct. But I believe that GLK needs an ACEA A3/B4 oil, meaning HTHS = 3.5+, so you might want to just run M1 0w40 without blending (or maybe just do a single quart of the 0w20 to thin it out to 3.6ish).

 

[BigJohn]

Originally Posted By: dparm
Yep, your math looks correct. But I believe that GLK needs an ACEA A3/B4 oil, meaning HTHS = 3.5+, so you might want to just run M1 0w40 without blending (or maybe just do a single quart of the 0w20 to thin it out to 3.6ish).



Good point and you are correct, but I could event get by with 7 quarts of 0w40 and 2 quarts of 0w20....which would be a HTHS of 3.55.


But seriously.....the oil would lab test with numbers, right in line with simple math?



.....

 

[Phishin]

For what it's worth, I was told by an old-timer on here that my mix of 2 parts M1 0w20 and 1 part of M1 0w40 would result in a middle of the road 30 weight oil.

I mix 1.4 quarts 0w40 and 2.8 quarts 0w20 in my Accord. So, I would assume that your mix would be a "thick" 30 weight....whatever that means.

 

[BigJohn]

Originally Posted By: Phishin
For what it's worth, I was told by an old-timer on here that my mix of 2 parts M1 0w20 and 1 part of M1 0w40 would result in a middle of the road 30 weight oil.

I mix 1.4 quarts 0w40 and 2.8 quarts 0w20 in my Accord. So, I would assume that your mix would be a "thick" 30 weight....whatever that means.



30wt is supposed to fall within: 9.3 - 12.4

5 quarts of 0w40 and 4 quarts of 0w20 would be 11.28....which would be a heavy 30wt.

You are correct.

But as I have done this research and math....I have to wonder if 'straight up', GC 0w30 would be even better?????

 

[Quattro Pete]

Originally Posted By: BigJohn
I have a simple question, that I suspect has a complex answer.

If I mix 4 quarts of M1 0w20 with 5 quarts of M1 0w40, what are the numbers?

If it is simple math (which I doubt it will be that simple), it would be the following....

Oil Weight

4 x 20 = 80, 5 x 40 = 200, 80 + 200 = 280, 280 / 9 = 31.1

So, is this blend and .... 0w31 ....?


But there is no such thing as 0w-31.

Xw-20, Xw-40 are just ranges of 100C viscosities and not actual viscosities. So why not use the exact viscosity numbers since they are known?

M1 0w-20 has a 100C viscosity of 8.7 cSt
M1 0w-40 has a 100C viscosity of 13.5 cSt

So, the resulting concoction would have a 100C viscosity of about 11.4 cSt, making it an Xw-30 grade.

I guess that's what you did further down in this thread. Sorry if I'm repeating what you've already done.

Personally, I wouldn't bother with mixing and would just continue with straight M1 0w-40.

 

[dparm]

You can largely ignore the KV values. Look more at the final HTHS. You need 3.5+.

 

[Roob]

Originally Posted By: Phishin
For what it's worth, I was told by an old-timer on here that my mix of 2 parts M1 0w20 and 1 part of M1 0w40 would result in a middle of the road 30 weight oil.

I mix 1.4 quarts 0w40 and 2.8 quarts 0w20 in my Accord. So, I would assume that your mix would be a "thick" 30 weight....whatever that means.


Just curious about the oil amount in your post. 1.4q + 2.8q gives you 4.2q or 3.97 litres. The 4cyl K24 accords spec 4.4quarts or 4.2Litres. Do you top off the oil or is this an oil change only but not a filter change?

 

[CATERHAM]

Originally Posted By: dparm
You can largely ignore the KV values. Look more at the final HTHS. You need 3.5+.

Yes he should pay most attention to the final HTHSV figure but whether he is needs a 3.5cP oil is entirely dependent on how John drives his Merc SUV.
Of course having oil gauges makes answering that question very easy, still without gauges for winter use one can very safely assume that your don't. 3 quarts of 0W-20 would still leave you with a HTHSV of 3.4cP which I wouldn't hesitate to recommend for year round use.
John's suggestion of a 4/5 blend giving a HTHSV of 3.3cP is still pretty conservative for winter use.

What I'd recommend would be a 50/50 blend giving a HTHSV of 3.2cP and I wouldn't fill the big sump to the max level but rather just over the minimum level and check it periodically to monitor the oil consumption rate. That will aid in heating the oil up faster and if you still have the mix in sump come the warmer weather you have plenty of room to add a quart of M1 0W-40 raising the HTHSV.

 

[BigJohn]

Originally Posted By: CATERHAM
Originally Posted By: dparm
You can largely ignore the KV values. Look more at the final HTHS. You need 3.5+.

Yes he should pay most attention to the final HTHSV figure but whether he is needs a 3.5cP oil is entirely dependent on how John drives his Merc SUV.
Of course having oil gauges makes answering that question very easy, still without gauges for winter use one can very safely assume that your don't. 3 quarts of 0W-20 would still leave you with a HTHSV of 3.4cP which I wouldn't hesitate to recommend for year round use.
John's suggestion of a 4/5 blend giving a HTHSV of 3.3cP is still pretty conservative for winter use.

What I'd recommend would be a 50/50 blend giving a HTHSV of 3.2cP and I wouldn't fill the big sump to the max level but rather just over the minimum level and check it periodically to monitor the oil consumption rate. That will aid in heating the oil up faster and if you still have the mix in sump come the warmer weather you have plenty of room to add a quart of M1 0W-40 raising the HTHSV.


Was thinking tonight that I would purchase a 5 quart jug of 0w40 and a 5 quart jug of 0w20 and go 50/50....at least in the winter. And maybe year around. This is not a turbo engine and high temps are simply not an issue at 7,000 feet elevation.

This is my wife's ride and she starts it up, drives 8 miles to work and shuts it off. Then the return trip. That is...mostly the life of this rig. We don't hot-rod or push this little V6 too hard. I want quick oil flow at -10F.....

Not worried about warranty.....


......

 

[CATERHAM]

With such a short commute and easy running, you could run M1 0W-20 straight without thickening it up at all at least for fall, winter and spring. In fact under those operating conditions, I'd use it year round.

As a point of interest, my older Porsche is spec'd for 20W-20 for temp's up to 60F and that includes hard running.

 

[Ayrton]

Obviously, you will choose what is best for you. Nevertheless, unless there is any noticeable issue, I'd just stick with the fully approved Mobil 1 0w-40.

 

[BigJohn]

I am at 50k miles on the GLK 3.5L and will be doing the oil change.... in a week or two.

I have decided to do 5 quarts of 0w40 and 4 quarts of 0w20.

Counting on this to be a great 'Winter Mix'

Thanks CATERHAM for the support!

Will run this mix for 10k miles and might do a Blackstone test.

 

[BigJohn]

All I can say is WOW!!!!

The car is incredibly more responsive and quicker....and so for the MPG has jumped from 21 to 23 MPG in the first 500 miles.

If the wife and I were driving this little 3.5L Benz aggressive and wild, I would stick with a 40wt....and if we were living in a hot climate, but I really like this soup in the sump so much better.

Heck, even the wife said, what did you different to my car. It is so much better.