Anyone here mix different grades of oil?

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Friend of mine has a 05' GTO with the 6.0, that he rebuilt about 6k ago. No supercharger on it, just rebuilt, car will see some drag racing. He's contemplating mixing about 3 1/2 qts of PYB 5w30 and 3 qts of Rotella 5w40. He read the Rotella 5w40 VOA and liked the add pack in the oil as well as the PYB's add pack.


thanks in advance,


adam
 
A lot of people mix oils. I've done 5w-30 and 15w-40, 10w-30 and 15w-40, 5w-30 and 5w-20, 15w-40 and 5w-20. Nothing special. You can google oil viscosity calculator to see what will come out.
 
If you mixed rotella 5w40 syn with pyb 5w30 or 5w20 what would you get? I cant get the viscosity app to load for me.


thank you in advance,

adam v
 
too many questions. Just mix 'em. If it has to be a perfect science for racing don't mix two oils.

Make sure you calculate the VI in.

I was just kidding about the too many questions part
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but in all seriousness, if you have to be sure don't mix them. It is going to be a thick 30 as I am sure you know. The math is kind of complicated with the ratio of oil mixed.
 
Thanks for that info Chubbs, and I kinda thought it would be a good or mildly heavy 30 weight. Friend says his gto says 5w30 is whats recommended, so cant be too wrong.


thanks Chubbs,

adam v
 
Originally Posted By: civic09
Friend of mine has a 05' GTO with the 6.0, that he rebuilt about 6k ago. No supercharger on it, just rebuilt, car will see some drag racing. He's contemplating mixing about 3 1/2 qts of PYB 5w30 and 3 qts of Rotella 5w40. He read the Rotella 5w40 VOA and liked the add pack in the oil as well as the PYB's add pack.


thanks in advance,


adam


In a vehicle that going to be beat on I won't mix any oil period... I'd run the Rotella or M1 0W-40...
 
Although I've mixed grades often, and brands in a pinch on vacation, don't think the time for an experiment is a drag race. If the engine breaks you will always wonder why.
 
Yeah, I told him that he may just be better off using straight 5w40 rotella instead of mixing the two. He has this gto as a daily driver anyways. He doesnt do much drag racing with the car either.

thanks guys for the replies

adam
 
How do you gauge success with mixing oils? If the engine doesn't immediately blow up? Unless you can evaluate the results scientifically, chemically, how do you know you have gained anything? More important, you may be losing versus just going with a single formulation. I thinking mixing oil often results in non-optimal results that aren't always apparent early on. Anybody that crows about it is blowing smoke because they can't prove any benefit over a single oil... except that the engine didn't blow up and maybe a decent UOA (which would have likely been just as good or better with either of the oils alone).

BUT, if you are going to mix oil, the best likely results (or perhaps the "least bad") come from choosing two with similar chemistries. The PYB and Shell combo likely meet this criteria, both being SOPUS products. But again, why mix when there are so many good, synergistically (not haphazardly) formulated products out there.

IMO, mixing sans data is for lawnmower and beaters.... and even then?????
 
Yes, many times with good results. But usually an admix, and usually not near 50/50, unless the grade and brand is close maybe. So, quite often it will be like, 3 qts A, 1.2 qts B. Or 3 qts A, 1 qt B, and .2 qts additives.
 
+1.
Why would you risk a recent rebuild using a probably okay mix of oils, when you can use a known good oil?
The savings aren't all that great, and chances are better than good that whatever mix you come up with will be inferior to either of the mixed oils alone.
Mixing is to use up leftovers on short runs where an engine will be in daily driver use.
It isn't for an engine which will be used hard, IMHO.
 
Originally Posted By: 4x4chevydude
Mixed oil is better than no oil...at least your engine is being lubricated no matter what I don't really see any harm here

And no special benefit. Oils are very complex chemical mixtures. It is possible that mixing different additive packages may result in a mixture that is less protective than either oil straight. Pick the oil you prefer and stick with it. If you're stuck and need to add oil, anything is better than nothing.
 
fdcg had some good advice. listen to him and pick one good oil and use it. At least you KNOW that a good rebuild has a GOOD oil.
 
Originally Posted By: Ken2
Originally Posted By: 4x4chevydude
Mixed oil is better than no oil...at least your engine is being lubricated no matter what I don't really see any harm here

And no special benefit. Oils are very complex chemical mixtures. It is possible that mixing different additive packages may result in a mixture that is less protective than either oil straight. Pick the oil you prefer and stick with it.


Agreed... In bulk oils we have to walk a fine line when mixing bulk tanks with our product and someone else's (brand and visc), especially old spec HDEO and CJ-4's. As far as PCMO oils, we don't recommend blending anything more than a 20/80 ratio. Again in bulk oils not engine crankcases but still applies.
 
It is not MY CAR, MY ENGINE or my problem guys. I think it would make for one heck of a VOA and UOA after 4000 miles honestly. Thanks for the negative vibes also guys and so ya folks know, Shell owns PENNZOIL.


adam v


Glad to hear that other members arent "afraid" to mix different brands, grades of oil also. I am posting this for a friend. Also the engine has over 10k since the rebuild also.
 
Nothing wrong with mixing different grades and I wouldn't worry about it at all even in a higher HP application.

If you were mixing like Valvoline with PYB then yeah I might hesitate but for your situation, using PYB and Rotella, you should be perfectly fine. I blend PYB 5w30 and PYB 10w40 to get the mix I'm looking for in my older 91 Civic. Typically 1 qt. of the 10w40 and then top it up with the 5w30. I can tell a difference in the way my motor performs with the blend and I prefer it to straigh 5w30.
 
Why would you want to mix oils? Do you know more about mixing oils than the experts?

Pick one oil and use it. Saying "It's all good" or "Won't be a problem" is just so much malarkey. Just because your engine doesn't immediately explode, it doesn't mean your mixture is better than any of the oils that went into it.
 
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