Mix of 3 Quarts Mobil 1 0W40/1 quart Mobil 1 5W20

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262
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St. Petersburg, FL USA
Per this website calculator, the final viscosity would be 12.42 at 100 degC and 69.4 at 40 degC. That would mean, if correct, this mix would be a very high 30, border line 40 (the cutoff at 30/40 is about 12.4 I believe). The 5W20 is thinner at cooler temps than the 0W40, and will only slightly help in cold starts, so it will bring it closer to a thinner oil like a 5W30 (Mobil 1 5W30 is 64.8 at 40 deg C). To answer your question in short, sort of. You'd probably be better doing a 50/50 mix, or actually run a 5W30. If it's for the Benz, I'd stick with the 0W40.
 
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1,714
Location
CA.
Not to hi-jack a thread but, maybe someone can help me with this. What happens to the xW portion of the equation when a 0W-xx is mixed with a 5W-xx? Or better yet lets say we mix 5w-20 Mobil 1 with 0W20 Mobil 1? Or even 5W30 M1 with 0W30 M1. What happens to the 0W or 5W part of the equation? Lets say they mixed in equal portions? Does it lower the pour point if they have two different pour points to start with? TIA AD
 
Messages
262
Location
St. Petersburg, FL USA
The pour point would be adjusted, but the xW is still in proportion to the base viscosity at operating temps. If I understand correctly, it would depend on the viscosity improvers present. A 5W20 is still thinner at cold (subfreezing) temps than a 0W40. I believe the pour points would average, but that may always not be the case, not exactly anyways.
 

MBCLK

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151
Location
Los Angeles, CA
 Originally Posted By: crosseyedwx
Per this website calculator, the final viscosity would be 12.42 at 100 degC and 69.4 at 40 degC. That would mean, if correct, this mix would be a very high 30, border line 40 (the cutoff at 30/40 is about 12.4 I believe). The 5W20 is thinner at cooler temps than the 0W40, and will only slightly help in cold starts, so it will bring it closer to a thinner oil like a 5W30 (Mobil 1 5W30 is 64.8 at 40 deg C). To answer your question in short, sort of. You'd probably be better doing a 50/50 mix, or actually run a 5W30. If it's for the Benz, I'd stick with the 0W40.
i actually want to apply this for my Honda or a Toyota 4Runner both of which spec 5w30. thanks for response crosseyed
 
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Messages
1,714
Location
CA.
 Originally Posted By: crosseyedwx
The pour point would be adjusted, but the xW is still in proportion to the base viscosity at operating temps. If I understand correctly, it would depend on the viscosity improvers present. A 5W20 is still thinner at cold (subfreezing) temps than a 0W40. I believe the pour points would average, but that may always not be the case, not exactly anyways.
Thanks for the reply. I had a feeling finding a direct proportion wasn't going to happen. In other words you wouldn't get something like a 2.5W-xx? AD
 
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