Mixing Different Oil Weights & Brands?

[cjcride]

Is not mixing different oil weights and brands unwise?
Had a Physics instructor say the chemical packages used by diff. brands may not mix well.

Thanks in advance.

Merry Christmas and Happy New Year

 

[lipadj46]

I do it all the time trying to keep my oil stock fresh and use up the opened jugs. The only thing that I can see wrong with it is dilution of certain anti wear additives. Lets say oil 1 relies on Boron and has little moly and oil 2 relies on moly with little boron and you mix the 2 in equal amounts you have cut down the moly and boron concentrations in half. Will that make a difference? maybe but probably not during a 5000 mile OCI.

 

[ThirdeYe]

Saying they won't mix well isn't true, all SM rated oils are formulated to be compatible. Now, they might not get the full benefits of the chemistry and you may want to shorten the OCI but it will still mix and work fine.

 

[Scienceman]

It will be fine. I do it in my diesel all the time.

 

[Eddie]

+1 ThirdYe. I prefer to stick with one brand & weight so I gain the maximum benifit from the oils chemistry add pack.

 

[PT1]

Your instructor is correct..but I never discard odd quarts of perfectly good oil and mix them in. Wasting it is worse...imo.

 

[fdcg27]

Originally Posted By: Eddie
+1 ThirdYe. I prefer to stick with one brand & weight so I gain the maximum benifit from the oils chemistry add pack.

Agreed.
I prefer to use one brand and weight.
However, I don't think you'll do any harm with a short run of a mix.
If you have a few oddballs laying around, go ahead and use them as a mix for 4-5K.
Maybe not optimal, but also not wasteful.
Of course, oddballs can also become lawnmower oil.

 

[tig1]

Let the lube engineers do their job.

 

[Steve S]

Originally Posted By: cjcride
Is not mixing different oil weights and brands unwise?
Had a Physics instructor say the chemical packages used by diff. brands may not mix well.

Thanks in advance.

Merry Christmas and Happy New Year
Can't believe what the physics instructors say all the time.

 

[HighViscosity]

Most oils have similar ingredients, so mixing wont cause any problems. I wouldnt go mixing oils for the fun of it though.

 

[dsmith41]

I don't do it. Orphan bottles go into the oil can. While all SM oils are technically compatible, I figure you could get a lesser degree of protection with competing add packs. Not the end of the world if you mix a small amount but I wouldn't do it on purpose.

 

[crazyoildude]

i see no problem with mixing oils people do it all the time i see people adding different oil all the time as long as the weight and rating are within reason there won't be an engine related problem there may be a problem with people like myself but thats only a mental issue that has to do with ocd... There seems to be a lot of us on here with different levels of that..Which is most of the time a good thing

 

[Whimsey]

I have multiple "orphan" quarts of oil, four Schaeffer's 5w30 SL, one quart of Motorcraft 5W-20 SL and one quart of Motorcraft 5W-20 SM. These are going into my 2002 F-150, 4.6 V-8 with a Motorcraft FL820S oil filter. This will run about 5,000 miles. Afterwards I'll revert back to my previous usage of Motorcraft 5W-20 oils with the FL820S Motorcraft oil filter. I hate to waste oil and with the cold cranking viscosity of the Schaeffer 5w30 Supreme Blend being practically the same as the Motorcraft 5W-20 I figure for 5,000 miles I'm "good to go" even through the winter months.

Whimsey

 

[charbaby]

I mix all of the time. I have so many qts of oil(syn & dino) that I try to make my own syn/blend. 2qts of syn & 3qts dino. Im not trying to play scientist/oil engineer but, Im just trying to give my engines pretty much the same blend all of the time. I changes a bit from winter to summer as far as how much 5W30 or 10W30 I mix, and when!

 

[demarpaint]

I've been mixing for a while too to use up some stray qts I have in my stash. Next OCI I will be mixing Pennzoil 5w30 High Mileage with Pennzoil 5W20 YB and a bottle of Lubro-moly Mos2. I'm hoping the High Mileage oil will slow a leak down, nothing I've tried so far has worked.

 

[otis24]

I have mixed the same oil, different weights. For instance, I had some Havoline 5w30 and some Havoline 10w30. My vehicles are now all spec'd for the 5w30. On a 4.5 qt fill, I have mixed 3 qts 5w30 to 1.5 qts 10w30 in order to use up the 10w30. I have also mixed half and half with Mobil Clean 5000 5w30 to use up my 10w30 old formula Havoline. The Havoline was purchased back when you could still pick it up on sale for 99 cents per quart. I have about 16 quarts left. During the summer, I will do an oil change using just 10w30 in order to deplete the stash.

 

[otis24]

I have also mixed 3qts Penn Platinum 5w30 with 2qts SuperTech synthetic 5w30 to use up the SuperTech.

 

[mechtech2]

As mentioned, if it says SM, it HAS to mix with other SM oils.

And like you thought, if one relies heavily on one method of additives than the other, you may end up will less than an optimal result.

But I see most common oils as pretty close in composition, and see no harm in mixing.

 

[JonfromCB]

Think of it as a "cocktail" for your motor..it may look alittle
different and it may taste alittle different, but it will still
have the desired effect.

 

[Jaymus]

I'm sure a car could go 200k on only one oil, or 5 different quarts and weights of oil each change.

But you got to think, the guys that made the oil put the additives in it the way they thought to work best. So, I usually try and stick with the same brand, and even same grade.

Think about it. Lots of oils are substituting lots of Calcium with Magnesium. Let's say you use one of those oils with 1200ppm of Ca and 800ppm of Mg. Then you add 2 quarts of another oil with 3000ppm Ca and no Mg.

I know it wouldn't 'hurt' anything, but is it what's best? Just food for thought.