Are there any adverse effects to mixing engine oil brands/viscosities?

i own a repair shop,and in case of an emergency its not bad to have to do this ,but it wont kill the engine,oil will mix together,its not like its going to separate inside the engine,but it is a good idea to try and stay with the right weight of oil,brand name isn't that important,but the weight of it does affect the viscosity of it,but your not going to kill if you add the wrong weight to it,all oils will mix ,other wise there would be lot of blown up engines out there right now,you should be ok as long as you change it at least every 3 thousand,good luck,i hope this helps.Are there any adverse effects to mixing engine oil brands/viscosities?
yes, just use one brand. Using different viscosities will probably not be good for the engine with different pressures in different areasAre there any adverse effects to mixing engine oil brands/viscosities?
The effect is cumulative, but if you mix grades, it's likely that one will dilute the other, which will cause thermal breakdown faster. I tried it once, and had to replace the engine a year later. (Surprised the **** out of me, I might add...)
I HAVE BEEN MIXING SYNTEC WITH NORMAL OIL FOR YEARS IT WONT HARM THE CAR AT ALL I'M A MECAHNIC FOR 13 PLUS YEARS
I'd say stick with the same viscosity. Brand wouldn't really matter because where does most oil come from? That's right, middle east. But if you are in an emergency, mixing wouldnt do more harm.
In most cases your vehicle will never know if you mix brands of oil.





Mixing viscosities may ';average'; their properties, but I would recommend sticking to whatever your manufacturer specifies for your vehicle to prevent adverse effects.





Having the proper oil level is the most critical. Clean oil is preferable to any dirty oil. Viscosity is probably more important than the brand of oil. Almost every brand of oil that you can buy today is of good quality.