Mix Oil Brands for Oil Change?

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I snagged some RP 0W-20 on closeout at Walmart. My wife sent me to Walmart to pick up a couple items. So I stopped by the auto section, and found 4, qt. bottles for $3 ea. The next day, when my wife had to make a trip to a neighboring town, I had her stop at Walmart and check for more. She found 2 jugs at $20.

As others have said, I've never tried RP, because I consider it to be way overpriced. But at $20, that's even cheaper than Valvoline Synpower. After reading of experience of race shops with RP, I'm a little hesitant about using it. But if I do, I had a question.

My Outback takes 5 qts for an oil change. Where I got the 4 qts of RP. Dare I mix 4 quarts of RP with 1 quart of M1 or PP, to bring it up to 5 qts?

Some of our most knowledgeable members here on BITOG have commented in a number of threads on the subject of custom blends of oils. I know they support blending different viscosity oils. But what about blending different brands of the same viscosity? Am I safe doing this? Or is there potential for different add packs not playing nice with one another?
 
Google the brands and look for the 'compatible with all oils' comment. They all say it.
 
Look at my current oil mix cited below. I am still waiting for my engine to implode.
wink.gif
 
Just found this on the RP Q&A page:
"Are Royal Purple lubricants compatible with other motor oils?

Yes. Royal Purple lubricants are fully compatible with mineral or synthetic oils. No special procedures are necessary when switching to Royal Purple.

However we do recommend doing a complete drain and fill as opposed to doing a partial top off on top of some other companies oil. We recommend against mixing different product lines or brands of oils from different companies, as it is not considered a best practice. Additive conflicts can occur in some cases when dealing with large quantities of mixed dissimilar engine oils."

And Mobil says this:

"Is it ok to mix conventional motor oil with Mobil 1 motor oil?

Yes. Mobil 1 is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 will be reduced by diluting it."

Mobil promises full compatibility, but a loss of their "superior performance" RP kind of beats around the bush, and implies that RP additives may not be fully compatible with all other motor oils. Considering that Mobil commits to ful compatibility, I tend to feel safe with the mix.
 
Originally Posted By: sicko
Check out: http://www.pqiamerica.com/March2013PCMO/Marchsyntheticsallfinal.html

Looks like it'd mix really well with NAPA Synthetic or Valvoline SynPower. I'd say wait until NAPA has their synthetic on sale for $3.79 a quart (they have it every couple of months), and pick up a quart.


Thanks. That's pretty helpful. It looks like Valvoline Syn Power is also very similar in makeup to RP.
 
For all the theoretical chemical incompatibilities mixing oils, frankenbrews have delivered good UOAs in the past.

It does get strange: Imagine combining M1's SuperSyn with Schaeffer's Penetro with Royal Purple's Synerlec, and then maybe thrown in whatever magic ingredient Castrol Magnatec has.
Do all these play well together? Makes you queasy, so most of us try not to mix.
 
Originally Posted By: sicko
Check out: http://www.pqiamerica.com/March2013PCMO/Marchsyntheticsallfinal.html

Looks like it'd mix really well with NAPA Synthetic or Valvoline SynPower. I'd say wait until NAPA has their synthetic on sale for $3.79 a quart (they have it every couple of months), and pick up a quart.


It does look like the PQIA VOA synth oils there can be divided into 2 groups: Those with sodium and those without. Also, you gotta wonder why Castrol Syntec and M1 use all that magnesium for detergents when nobody else does. Compatability? Maybe.
 
OP, your initial inquiry didn't give me the impression you plan on making this a habit so i wouldn't worry one bit. And even if you were, most folks just read the bottle (where they say fully compatible) and move on.
 
I would just spend the extra $ and buy an extra quart of Royal Purple. I cant bring myself to mix brands / grades etc. There are too many different add pack...packs...and I would be worried they would compete to lay down there additives, possibly causing more wear. Can you mix them? YES! Is is optimal, maybe not.
 
Originally Posted By: robo339
Just buy one quart of rp to make up the difference it's definitely not going to break the bank



+1

Not going to hurt unless you need to do the changes like now...
 
No worries whatsoever but wow, if I'm reading right you've got a 2 jugs plus four loose quarts so you could just put in 5 quarts and be done?
 
Originally Posted By: BHopkins
Mobil promises full compatibility, but a loss of their "superior performance" RP kind of beats around the bush, and implies that RP additives may not be fully compatible with all other motor oils. Considering that Mobil commits to ful compatibility, I tend to feel safe with the mix.

It's certainly safe, but there are some concerns. M1 EP has a 15,000 mile warranty. XOM isn't going to give you a prorated warranty, or likely any warranty whatsoever, once you start mixing. RP also has a mileage warranty.

And, when it comes to UOAs, those should be trended, otherwise they're not terribly useful. Blends and bouncing around from brand to brand do not lend themselves well to trending.
 
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