Mixing quarts of different oils to make a full oil change

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Jul 31, 2003
It has been discussed before about mixing brands and weights of oils together to come up with a "perfect" home brew.

I'm actually asking about this because I have 7 different bottles of oil in my basement that I want to get rid of. I will be ordering some Amsoil ATM this week, and in the mean time wanted to flush my truck with the following:

1/2 qrt of M1 0w-40
1 qrt of M1 10w-30
1 qrt of GC 0w-30
1 qrt of Penz. 5w-30
1 qrt of QC full syn 10w-30
2 qrts of Delo 15w-40

This oil change is to serve two purposes. One is to get that retched RP 5w-20 out of my truck. The truck is noticably tapping and clicking and vibrating all the time now. I will be sending a sample in, however the noise is really starting to concern me now. Second, I really need to get rid of all these lone bottles of oil. The reason I have them to begin with is that I usually buy an extra bottle to top up with when I do a change. Ironically the only oil I needed to top up with is the RP 5w-20 ( a full qrt) and M1 0w-40 (1/2 qrt).

OK - now to my question. Will there be any harm in running this mix for a couple weeks? Does anyone think that the oils will react badly with each other?
I would have no problem running that brew for a couple week flush. Actually, you probably could run it 3000 miles.
How about you run it for 3k and do a UOA just to see how it performed!
Well I did use this combo. But before I go further I have to apologize. I promised to sample the 5w-20 RP and get a UOA, which I really wanted. From the noises my engine was making, I was certain that this had not only sheared down, but was showning a huge increase in wear. The truck had delevoped a bad case of piston slap, or it just got much louder anyway.

Funny thing with this oil. I pulled the drain plug, and reached for my sample bottle accidentally knocking it over. By the time I got the bottle to the crankcase it was empty! 6 qrts of hot 5w-20 came out looking like boiling tea! It splashed everywhere and took less than 2 seconds to empty completely.

So again, I 'm sorry. I'm sure this would have been a pivotal UOA, because of the racket my engine was making. The piston slap was getting worse by the day. The "brew " seems to have helped, but its still there in the mornings.
Wow, that's some brew hehe, you better do a UOA on it! j/k its your money
Hope the piston slap goes away, i get some in my LT1 on cold days, just let your car warm till it goes away before you drive around, thats what i do....
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