Does mixing oils work?

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282
Location
Central Valley, CA
For example, if one were to take a synthetic 5w20 and mix it with a synthetic 5w30 of the same brand, then would you end up with a 5w25, or just a crankcase that's 1/2 5w20 and 1/2 5w30? Reason I ask is I've got a few leftover quarts of Mobil 1 0w40, plenty of 10w40 HM, and for some stupid reason bought a few quarts of 5w40 TDT today. I've been running 10w40HM as of late in the Mercedes, but have given thought to making a Mobil 1 "super mix" for the next oil change, with 1/3 0w40, 1/3 5w40 TDT, and 1/3 10w40 HM... How does that sound - a Mobil 1 5w40 Turbodiesel High Mileage that meets MB229.5 spec...
 
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1,084
Location
Florida, USA
Not sure about the certifications, but mixing is no problem for the oils you mentioned. All motor is blended using several different components.
 
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5,573
Location
earth
i don't think it gives you any benefits whatsoever other than using up odd volumes of oil left over from previous changes.
 

dnewton3

Staff member
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8,459
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Indianapolis, IN
If you really want to know what would happen, mix them all, and send it off for a VOA. You'll know exactly what the vis would be. Then run it for 5k miles and see how well it works. I suspect it'll come back about as "normal" as anything else in a UOA, regarding wear metals. Sure, the add-pack will seem a bit funny looking, because the individual components will representent different products. But the better today's lubricants become, the more homogonized the results in a UOA, for shorter duration OCIs. In other words, the more refined (pardon the pun) today's oils are, the more likely they are to perform to a set minimum standard. Longer OCIs will bring out the distinctions, but shorter OCIs and the resultant UOAs tend to seem similar, if not the same, because the oils have not had time to distinguish themselves yet. So by blending different products together, and using them for a short term (5k miles or less), I doubt you'll be able to tell much difference. Why not try it. Run both a VOA and a UOA. Then post up all the numbers, but DO NOT tell us what the actual products are, or what percentages they were mixed at. I doubt people would be able to tell the difference by the UOA. Sure, we'd all guess and some might get close, but the reality is that the hybrid blend wouldn't do much to distinguish itself in such a short run. I have toyed with this idea myself. Get 4 different branded quarts of bargin oil from several sources and viscosities, run them in my wife's minivan (3.0L Nissan) for 5K and post up the results. See if anyone can tell me what brands I used, and see just how terrible the real wear metals would be, with such a "mutt" of an oil blend. Sometimes it's necessary to put the oil-biggot perspective in check. ;\)
 
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12,978
Location
ROCHESTER, NY
I don't know if mixing oils hurts anything. Many say that there is addative clash and others say that your changing the chamistry of the oil. Years ago when I was young, had no money and drove junk cars, I would use what ever oil I could get my hands on(not steeling it), just left over qts of oil from friends/family and self. I'd use 5 different brands, each being a different grade. Never had any engine issues due to the oil I was using. After discovering BITOG in '04/'05, and reading the "Product Rebates/Sales" section, I have had an oil stash like I have never had before. Prior to discovering BITOG, I would buy 1-2 cases of oil on sale w/rebate and call it good. These days I have in access of 60 qts at a time. All different brands/grades of dino and syn that I purchaced cheap on sale/closeout/rebate and even FAR! Because I have far less syn than dino, I like to add 2qts of syn to 3qts of dino and call it my blend. Trying to stay with the same 2 syn's and the same 3 dino's, it doesn't always work out that way. Sometimes I use 2 different syn's and 3 different dino's and my engines run perfectly smooth with good mpg. I think that engines and oil are so good today as compared to when I was a kid(35 + years ago) that there should be no issues that your engine will notice. My lawn/snow equipment see nothing other than the residual oil left over from each qt/OCI. What I mean, is that after an OCI, I tip over all of my qts of oil and let them drain into a wide mouth qt(Mobil 1 container). I do enough oil/filter changes on enough vehicles to keep my equipment supplied with using the residual oil. My equipment runs beautiful! I haven't done any UOA's but, I have put on as many as 300,000+ miles on vehicles doing this without any rebuilds and have run my lawn and snow equip in access of 20 years all without oil related issues. I don't think that the engines give a hoot! It's everything else that wears out. Just my experiences! CB
 
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34,964
Location
NY
I always tried to stay with the same oil and grade, and for the most part I still do. Since joining BITOG my beater sees what ever is on sale, and I have no problems mixing oils. If I want a synthetic blend I feel I can mix a better blend than I can buy. I do try to stick to the same brand oil when mixing a blend, but I doubt it really matters. My lawn mower sees what ever I have left over, and after 12 years it is running like the day I bought it. It is properly maintained, certainly not neglected. Having said that my new Jeep and treasured E-150, get top shelf synthetic oil. Not sure it makes any difference, but I feel better about it, maybe its just the placebo effect When they graduate to beater status, they'll get mix and match dino.
 
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1,084
Location
Florida, USA
 Originally Posted By: dnewton3
Why not try it. Run both a VOA and a UOA.
Why not? Because it would cost money to do those tests, and the whole point is to save money by using up the oil he has on-hand.
 

PT1

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5,746
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near the mistake
 Originally Posted By: Mark888
 Originally Posted By: dnewton3
Why not try it. Run both a VOA and a UOA.
Why not? Because it would cost money to do those tests, and the whole point is to save money by using up the oil he has on-hand.
Exactly...why spend $44 on the analysis?
 

opposite_locker

Thread starter
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282
Location
Central Valley, CA
My basic question is: Will the oils actually mix to create a middle-ground weight with the benefits of each oil realized (albeit each to a lesser extent)? In other words, will each square millimeter (for example) of a bearing be lubricated with either 0w40, 5w40, or 10w40 at any given time? Or will each square millimeter (for example) be lubricated by the conglomerate mixture? I realize this is a bit of a ridiculous question that can probably only be answered by the people that actually developed these oils, but I'd love to hear the opinions of all you oil-nuts.
 
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1,084
Location
Florida, USA
 Originally Posted By: opposite_locker
In other words, will each square millimeter (for example) of a bearing be lubricated with either 0w40, 5w40, or 10w40 at any given time? Or will each square millimeter (for example) be lubricated by the conglomerate mixture?
Conglomerate.
 Quote:
I realize this is a bit of a ridiculous question that can probably only be answered by the people that actually developed these oils, but I'd love to hear the opinions of all you oil-nuts.
Actually it can be answered by someone other than the the ones who developed the motor oil. As I said previously, motor oil is made from blended base stocks and additives. If you look at all the various types/viscosities of Mobil 1 (more than 15 different ones sold in the US alone), it is obvious that they don't manufacturer 15 different varieties of PAO. They blend different PAO stock (along with some Group III hydrocracked stock). along with various additives, to come up with each viscosity. It is perfectly OK for you to blend your own motor oil, using oil from a bottle that has already been blended. Mobil has said as much in their FAQ.
 

opposite_locker

Thread starter
Messages
282
Location
Central Valley, CA
Good enough for me. Unfortunately, I'd rather spend my money on oil than actually having it analyzed. So once I give this mixture a try at the next OCI, I will only have subjective (and therefore totally irrelevant) results to post.
 

KW

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1,686
Location
Central Arkansas
Several years ago I was mixing M1 5W30 and 15W50 to make up a 10W40ish oil for my Jeep. This was before M1 made a 10W40 oil. The mix worked well for me as far as I can tell for several OCI's. Before I started mixing the oil I contacted M1 and they said that I can mix the oil until my heart was content. My daughter used to have a Dodge Shadow that used a little oil and she dogged the car -- so it got a mix of what ever left overs were out in the shop at the time of the oil change.
 
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