Mixing oils to create your own blend!

[AEHaas]

Saying that oils are compatible means chemicals will not gell or precipitate out of solution. It does not mean they work well together.

Let’s say one oil uses chemical F for its high temperature anti-friction component. It works best at a particular concentration. It may be less effective at a lesser concentration, hence, one of the reasons that we need to change our oil. As you drive the component is used up, the concentration decreases below a critical level.

Another oil may use anti-friction additive G to do the same function. An oil change is required as this additive falls below it’s most effective concentration.

If you mix both these oil together in a 50-50 concentration you will dilute each of these additives by half at the moment you start to run this oil concoction. It is unlikely that a few thousand miles down the road you have the appropriate protection you were expecting of your mix.

Further, even though a mix of several Base Oils of different grades may give you a close approximation of final viscosity, all bets are off when mixing fully formulated oils as again, components may start out at half strength. Some additives do no do their intented task on a linear scale. A certain minimum concentration may be needed for the additive to begin to do what it was designed for.

I do not like mixing motor oils of even the same brand.

aehaas

 

[Eddie]

I totally agree. I was taught many years ago to not mix oils and try to get my own mix to be better than the people blending at Pennzoil, Mobil etc for the same reasons mentioned above. Ed

 

[FutureDoc]

Oils must be mixable... there is nothing "wrong" with mixing oil but you might get a odd product. It will not hurt anything but it might not benefit anything either.

If you are mixing two oils with different add-packs, you could be diluting something, like Mg or Mo. On the other hand, many oils are very similar that mixing will not really change the composition all that much.

I have not seen any UOA of "mixed" oils that really makes me worry... because 2 of my 3 cars uses less than 4qts, I almost always have leftovers that often make it into the othe car every so often.

The real difference between M1 and PU is that M1 has more Mg and PU has a bit more B... both will remain above average other oils even when mixed... so who cares.

 

[KCJeep]

The UOA's I've seen of the "Caterham Blend" seemed to produce the expected result. I did one UOA of a blend myself (same oil no less just different weights) and ended up with a much thinner lube than I expected. I have long attributed it to Castrol changing formulas without updating their specs, but it could also be an indicator of the unpredictability of blending.

Now that I think about it I did a UOA with another blend on a smaller scale (all PYB 10w40 with 3/4 qt 5w20) and also ended up with a lighter than expected result. At 3,500 miles kv100 was 10 and I expected higher than that.

Hmmm....

 

[Brule]

Originally Posted By: crazyoildude
yup you never know when you have to go out and start your car at -65 degrees F


pretty sure rw19 was asking about pour point of Amsoil in order to guess at the base stock

 

[justinh384]

If oils were not mixable, then what would happen to the countless cars that are topped off by the masses with a completely different brand than what is in the sump? I know mixing will not benefit you most of the time, but I do not see it hurting much of anything either.

 

[901Memphis]

Some play it safe some Franken blend. Nothing any worse than someone who never changes their oil.

 

[KCJeep]

Originally Posted By: justinh384
If oils were not mixable, then what would happen to the countless cars that are topped off by the masses with a completely different brand than what is in the sump? I know mixing will not benefit you most of the time, but I do not see it hurting much of anything either.


No it certainly won't "hurt" anything but intentional blending is not always going to achieve the expected result IMO, Widman calculator or not.

 

[widman]

Originally Posted By: KCJeep
Originally Posted By: justinh384
If oils were not mixable, then what would happen to the countless cars that are topped off by the masses with a completely different brand than what is in the sump? I know mixing will not benefit you most of the time, but I do not see it hurting much of anything either.


No it certainly won't "hurt" anything but intentional blending is not always going to achieve the expected result IMO, Widman calculator or not.


The only thing considered in the calculator is viscosity. While it works well for motor oils, and different brands are "compatible" you don't get the full protection intended by mixing brands, just as you don't when mixing with the residuals on each oil change.

 

[justinh384]

Originally Posted By: KCJeep
Originally Posted By: justinh384
If oils were not mixable, then what would happen to the countless cars that are topped off by the masses with a completely different brand than what is in the sump? I know mixing will not benefit you most of the time, but I do not see it hurting much of anything either.


No it certainly won't "hurt" anything but intentional blending is not always going to achieve the expected result IMO, Widman calculator or not.

Well my statement wasn't directing to intentionally blend different brands when you change your oil. I was simply referring to the countless cars that are topped off by the owner with a completely different oil because they don't exactly know what oil is in the sump. At the very least, isn't a car with the optimal level of oil better than a car that is one or two quarts low? I am referring to the average consumer. Many do not change their own oil and do not have an interest in what the shop, dealership, or quick lube uses. At least some of the average consumers KNOW how to check their oil level.

 

[fdcg27]

My first thought would be to ask why.
If you really wanted to, there should be no problems with basestocks, since the two can only use varying proportions of the same basestocks and their add packs are more alike than different, but why?
I'd use either straight.
No problems are likely mixing the two, but what do you hope to accomplish?
You won't likely end up with an oil superior to either on its own.
IMHO, the only reason to mix oils is to use up some leftover orphan quarts.
There are some well respected members who would tell you to mix away as a means of adjusting viscosity, though.