Hey guys. Yesterday i was watching my uncle change the oil in his '06 suburban. He drained the oil first, then he decided to see if he had any oil. Its a 6 quart system and he had 4 quarts of castrol 5w30 synthetic so he dumped that in, then he dumped in some 10w30 synthetic valvoline. I asked him why he would go through all the trouble of changing the oil only to mix two different brands.. he said it didnt make any difference.

So the question is: is it ok to mix different brand oils? I've heard that if you mix two different brands, some of the additives can "cancel out" is this true?
I would never mix two differnet oils in my truck unless it was just a quick top off shortly before an oil change, but i always keep a quart of what i have in the motor with me since i ocasionaly have to add some.

What do you guys think? Did i make myself look like a dumass by making a big deal out of this?

thanks

 

I'm not an expert but from what I've read on BITOG there is no issue w/ mixing oils.

 

Different weight oils do not mix...Period..
Different branded oils of the same weight may still have troubles mixing!

It's reccomended not to mix oils of different brands or weights.

 

i agree with dogg on this one i have read the same thing

 

While I'm not inclined to do it myself, mixing 2 cheaper oils like the ones mentioned which are both 30wt is not gonna cause a problem. He basically just made a blend kind of like motorcraft's synthetic blend. I'd say if he wants a blend just go to walmart and buy the motorcraft or castrol blend. If you really want info from people obsessed w/ maintenance and oil post it over at BITOG.

 

synthetic blend is synthetic blended with dino oil i believe. oil is still oil but when you mix grades you don't know what you get.

 

different grades do not mix well, and different brands with their different packages of additives can be worse. I've read reports where a lab mixed a couple different brands and got one hell of a sludge problem within the first couple hundred miles of simulated use!!!

 

I sure wouldn't mix unless it was an emergency. Really crap like that makes it scary to buy a used car or truck.

 

ok guys, good to hear... i hate being wrong.

tlawre- your sig is fuchin hilarious... "my name is trevor and my tank is empty" LOL
those commercials are so stupid they embarass me

 

haha thanks man. I first seen the commercials then went out the next day and look at my gauges. WTF?!?!?! Mine sure isn't full. The fuel light was on.