Originally Posted By: OneEyeJack
If you mix oils how do you know if the resulting mix would meet the spec's for either donor oil? You can mix engine oils any which way you like because they are miscible but why not just pick an oil and stick with it? Let the formulator do his/her job. For me, I'll admit that beyond a UOA I don't know what goes into designing a finished product that sits on the shelf that meets the spec's listed on the bottle. My answer would be, of course you can mix the oil, dyno or synthetic but I prefer to stick with one brand and viscosity.
Well, let me see if I can explain this!
1) I don't try to out think the oil engineers or blenders. I just try to use up oils in my stash. Sometimes this requires using different brands/grades.
2) 40 something years ago, I used any oils for my OCI due to low income and a beater car. Sometimes these OCI's consisted of 5 different brands each being a different weight.
3) Today, I will make my own blend(2qts syn/3qts dino) as I buy all of my oils on sale/rebate/discounted or discontinued!
4) All of the oils that I use today are oils that are held in the highest regard here at BITOG or other known forums. Every oil that I use, meets spec so, mixing them together doesn't bring them out of spec. This has been shown in UOA's by others here at BITOG, using a Frakenbrew!
5) I don't just go around mixing oils, just to mix oils(as I did 40+ yrs ago). I mix to use up precious resources for a decent OCI. Or for my OPE and in over 40 years of doing this(on occasion), I have never killed an engine. Many engines had over 200K-300K miles on them! Many of these engines had mixes of oils you wouldn't believe!
6) Do I think that mixing is optimal? NO! This should probably be #1 not #6
7) I mix because I can!
I don't want to just use one brand/grade and I like to buy by price...Known/regarded oils! And this too, creates straggler qts of oils.
8) I don't promote mixing oils together but, I will tell others that mixing isn't going to hurt your engine as long as you are using the correct grade/weight/spec for your engine listed by the MFG. Even using thicker/thinner oils together won't hurt the engine but, user be aware of climate changes and the grade/wgt's of oils you are using.
There is probably #'s 9 & 10 but, I can't think of anymore!
Hope this helps to clear this up!
