Mixing 5w30 w 10w40 4:1 to reduce stash???

[FlyNavyP3]

Originally Posted By: fdcg27
Yes, you can use a viscosity calculator formula, which seem to work pretty well at the higher end of the temperature range while not as well at really cold temps.
Google Widman viscosity calculator bobistheoilguy and you should find a thread with a link.


Awesome, thank you so much. This was really helpful.

Using this calculation it predicts that a mix of 3 quarts Napa Synthetic 0w20 with 2 Quarts of my 10w40 MC yields a cSt @ 40C of 74.79 and cSt of 10.64 @ 100C. So that should put me right where I want to be for a target of a 30wt oil in my 4Runner and perhaps the Lexus too!

 

[FlyNavyP3]

A little bit of thinking on this still.

Would I want to shoot for the top of the 30wt band when blending the middle or the bottom?

0w20/10w40 3:2 yields cSt of 10.64@100C
0w20/10w40 2:3 yields cSt of 11.95@100C
0w20/10w40 2.5/2.5. cSt of 11.27@100C
0w20/10w40 4:1 yields cSt of 9.50@100C

What are your thoughts? Vehicles it's used in run 185 and 192 F respectively on the water temp, the vehicle that runs 192f has an oil cooler, the other does not.

 

[KL31]

Might as well shoot for the top, especially if you have much of the 40 remaining. Castrol edge runs near 12 and that's 5w30. Plus with a little fuel dilution or shearing down, being near 12 won't hurt.

 

[gfh77665]

Originally Posted By: FlyNavyP3

0w20/10w40 3:2 yields cSt of 10.64@100C
0w20/10w40 2:3 yields cSt of 11.95@100C


If you really want to optimize, use the "0w20/10w40 3:2 yields cSt of 10.64@100C" in the winter, and the "0w20/10w40 2:3 yields cSt of 11.95@100C" in the summer. Both will work great, I speak from vast experience.

Keep it simple, so don't use partial quarts. It not worth useing the (2.5 + 2.5) mix.

 

[FlyNavyP3]

Originally Posted By: gfh77665
Originally Posted By: FlyNavyP3

0w20/10w40 3:2 yields cSt of 10.64@100C
0w20/10w40 2:3 yields cSt of 11.95@100C


If you really want to optimize, use the "0w20/10w40 3:2 yields cSt of 10.64@100C" in the winter, and the "0w20/10w40 2:3 yields cSt of 11.95@100C" in the summer. Both will work great, I speak from vast experience.

Keep it simple, so don't use partial quarts. It not worth useing the (2.5 + 2.5) mix.


I was thinking exactly that I really didn't feel like using partial quarts. Here in Florida I'd likely use the "summer blend" all but 1 OCI per year as we only have about 1-2 months per year where temps are below 40 overnight and those mo this temps are usually in the 60s during the day! I really appreciate everyone's input. I will be trying it on the next OCI in the Lexus and 4Runner.

 

[FlyNavyP3]

Sample taken awaiting results for a 3:2 blend of 10w40/0w20. Oils used were 2 quarts Valvoline MaxLife 1 quart Valvoline DuraBlend 10w40 & 2 quarts 0w20 Napa Synthetic. 5,200 miles on sample.

 

[FlyNavyP3]

Oil changed in the truck with the home blend listed in the post above. Waiting for the Blackstone results. Another home blend went in. This time it was 3 quarts of Napa Synthetic 0w20 and 2 quarts of Valvoline 10w40 Motorcycle oil. Will run this second batch another 5,000 miles. I will post the results here when they come back from the lab on the first run.

 

[FlyNavyP3]

Just wanted to follow up on this, UOA is back for my first blend.

This oil report is for a 0w20/10w40 2:3 yields cSt of 11.95@100C from my calculations back when this thread was started. Oil used was 2 quarts 0w20 Napa Synthetic 1 quart Valvoline Durablend SM 10w40 and 2 Quarts Valvoline MaxLife SM 10w40. I suspect the higher iron despite the highway run is due to the extended higher RPM running this truck experiences while nearly exclusively highway tripping (~3000-3500 RPM) when compared to my city driving where engine speeds are normally under 3,000. Additionally highway driving requires significantly more throttle input to maintain speed compared to city driving. The current fill will likely be mostly city driving again so it will be a nice comparison. I think the viscosity calculator was pretty darn close on this blend given the UOA results.

Enjoy!