Mixing Oil of Different Viscosities

[EMCD]

is it bad to mix Oil of Different Viscosities? like 10W/40 with 20W/50?

[cudabob496]

no, will just get a viscosity in the middle somewhere

[EMCD]

I figured it was ok, but I thought I'd ask the experts. Thanks for the reply!

[dodj]

no, will just get a viscosity in the middle somewhere

I'm no oil expert, but if you mix different greases I know you can end up with something that is not very slippery. It depends on the make-up of the grease and what others it will mixes well with. I would not mix oils unless I had no choice or I had definitive proof/reasoning as to their compatibility. 

[cudabob496]

I figured it was ok, but I thought I'd ask the experts. Thanks for the reply!

We are only experts of our opinions

['Cuda Hunter]

I have mixed all kinds of oil over the years.  Never had a problem. 
Even old oil.  As long as it has a viscosity and weight rating I will use it. 

You know the oil that came in the paper cans.  I purchase a few of those a year at different auctions.  I use it up.  Works fine. 

[EMCD]

I have 3 quarts of Brad Penn 10W/40 that I'd like to use with a 5 qt jug of 20W/50 Lucas hotrod oil. Can you see any issues? I'd like to thinken it up a bit for the hot summer weather.

[jhaag]

Can't imagine any scenario that I would do this. Right or wrong why would you mix oils from different companies, with different additive and detergent packages? Same company maybe. Different manufacturers, no way. Might not make any difference, but oil is relatively cheap. Why reinvent the wheel by trying to change viscosities? 

['Cuda Hunter]

I would do it.  It's just gonna last 3 to 5K miles and be changed out anyway.  What are the additives going to do to each other?  oil is oil is oil. 

Now I will say that I do have one car that I don't mix anything in.  I'm very specific about anything I do to that car.  But I have owned it since new so I'm just a stickler about that one car.
So if your a stickler about your car, this could raise doubts in your mind as to whether the engine will be ok.  Don't do it if your going to convince yourself something is wrong with it.


My opinion of course.  I'm no oil scientist.  I am an oil consumer.  Of which I am fed tons of different types of oil at the stores.  Every brand has something "different" and "better" than the next brand.  My opinion is big oil companies are just shoving that crap down our throats.  Oil is oil.  All of which is designed to go in our engines. 

Now on another note, I had a friend who had a really bad rear main leak.  It would just throw oil out of it.  So my friend took all my used oil buckets and any other that he could find to drive this vehicle for a short while.  Drove it thousands of miles until he got another vehicle.  Just basically doing an oil change every day with absolutely used up oil.  Still drove fine.  didn't care about different fiscosities or brands or anything.  Hell, metal chips for that matter.  he used some oil that had a 383 bearing exploded in it.  Engine never noticed the shavings. Mixed everything in that one.  Even some old oil that had only the viscosity and no weight specifics.  OLD oil.   

[Katfish]

No different than mixing different brands of bottled water.
As stated, "oil is oil", don't let all the marketing stress you.....

[brads70]

I often get to customers houses and they say "I have this old oil I've had for 5-10 years here in the garage, can you dispose it?"
I reply well it's been in the ground for a lot longer than that I'm pretty sure it hasn't gone bad. 

As for mixing viscosity's ? I'd say it doesn't matter/won't hurt anything.  Performance engines are built with more clearances so use the viscosity/brand of oil the engine builder recommends I use 20-50 in mine. 

[1 Wild R/T]

This discussion reminds me of when Richard Pryor said  " I dipped my cookie in the milk and the **** blew up!" 

[ChallengerHK]

I'd be more concerned about additives that didn't play well together than I would about viscosity.

[Racer57]

With all of the threads in this forum about people that mixed oil brands and/or viscosity and had their engines blow or seize up, I'd be scared to do it !!!

[1 Wild R/T]

With all of the threads in this forum about people that mixed oil brands and/or viscosity and had their engines blow or seize up, I'd be scared to do it !!!

   Any links....