Who here blends viscosities when changing oils ??

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Nov 28, 2002
Triad, NC
I have begun to blend oil viscosities a little.....i.e. 4 qts M1 5W-30 and 1 qt. M1 15W-50.......
What are you doing and why? results, problems???
In the hot summer months I sometimes blend 4 quarts of 10w30 Redline with 1 quart of 20w50 to give me a 12w34 or 3 quarts 10w30 with 2 20w50 for a 14w38. I don't know why, but somehow I feel this is better than using their 10w40 oil.
Well, one of my cars has 2 quarts of Pennzoil 5W-30 synth blend, one quart of Pennzoil 15W-40 Long Life and one quart of Quaker State 15W-40 HDX in there right now. Why? These were what I had leftover after cleaning out my stash of Wal-Mart closeout $0.69/quart containers! I figure there's a 10W-35 blend in there now with a little Moly and some other good stuff. It's only going to 3K or so, anyway!
Well I am trying a blend right now. I was short on cash and needed an oil change. So I tried 10W30 Chevron Supreme group II+ base stock. I had a quart of M1 15W50 so I substituted it for one quart of Chevron Supreme 10W30( 3 quarts of chevron and 1 quart of M1 15W50). I felt better about this then running just Dino. This is the first time since 1988 I have ran a dino oil in a car or truck. I also felt better because I had seen that Chevron Supreme especialy 5W30 thined out of grade in a couple of UOA in as little as 3000 miles. It still had good numbers though. My car is able to turn 8000 RPM's and I run it between 4000 and 6000 pretty at least twice a week. This blend is going to be my base line for this car when I do a UOA.

I am probably going to buy a case of either Delvac 1 or Redline soon so I do not have to worry about needing oil for oil change between pay checks! It is just my income now so I find that I can not always buy things when I need them. I often have to wait longer then would be ideal or save up. For anyone interested I typed in delvac 1 in google and one of the sights that came up had 4 gallon case for $83.00. I had to restore my system so I lost the site.
On our 88 Camry, I have used 2 5W30 and 2 10W30 Pennzoil dino year-round for years....we have since sold the car (at 294,000 miles) to my wife's sister and they switched over to high mileage Pennzoil 10W30.........car just turned 297,000 miles this past week....still running great.
I'm currenting using 3qts Mobil 1SS 10wt30 and 1 & 1/2qts Amsoil S3K 5wt30 HDD in my Subaru Outback wagon. I had a good UOA report using the above Mobil 1 and heard good things about the Amsoil, especialy about how it's additive package maybe better suited for sever type of driving. Since I wanted full synthetic and Amsoil is about $2 more a quart and and try to save a few bucks, I mixed the 2. So far no leaks or consumption....engine sounds normal.

Someone in the distant past posted a chart or formula for figuring the resultant viscosity when blending oils of different viscosities. It is NOT an arithmetical average.

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