Mixing Group III and Group V Synthetic Oil?

[Chuck1986]

A little while ago I stocked up on some NAPA synthetic that was on sale. Recently, when Castrol Edge went on sale I did the same thing - I just couldn't resist the low price and its very promising low temperature flow numbers, it's perfect for where i live!

My question is, is it OK to do a 50/50 blend of the NAPA synthetic (group III) with the Castrol Edge (group V)? I don't want to get rid of the NAPA synthetic, yet I also don't want to use it by itself because I'd like to reap the benefits of having a group V oil in the crankcase. I suppose my main concern would be incompatibility with the seal swelling chemistry of the oils. Both are 5w-30 and I have 65k miles on my Eclipse V6 6g72 engine.

Thanks!!

 

[Johnny]

When did Edge become Group V?

 

[Chuck1986]

Originally Posted By: Johnny
When did Edge become Group V?


I heard it from a bird

 

[rg200amp]

Use one at a time.

You DO NOT get a super oil when you mix two oils.

All you GET is TWO diluted motor oils.

 

[Chuck1986]

Originally Posted By: rg200amp
Use one at a time.

You DO NOT get a super oil when you mix two oils.

All you GET is TWO diluted motor oils.


The intent is not to get a "super oil".
I just was hoping the blend would be safe and allow me 1/2 the potency of the NAPA synthetic and 1/2 the potency of the Edge. I'm not hoping for anything synergistic.

 

[Chuck1986]

My bird just came back and said Edge is NOT group V, but a group IV. Sorry for the confusion.

 

[pbm]

"Think with your dipstick" and use them seperately. They are both good oils and you should be able to go 6 or 7.5K on the NAPA in most applications.

 

[BuickGN]

Originally Posted By: Chuck1986
My bird just came back and said Edge is NOT group V, but a group IV. Sorry for the confusion.


I'm pretty sure it's a blend of III and IV at best. Regardless, I don't like mixing just due to the unknown. I'm sure you won't have any issues but why take a chance? FWIW, in my beater commuter '87 Celica I used all of the 1/4-1/2 quarts of different brands leftover oil I could find to make a 4 quart fill. Never had a problem but the car was only worth $500. I wouldn't try in in my current cars.

 

[daves87rs]

I wouldn't.

 

[Neil_A]

No mixing, just pure EDGE! Now that's thinking with ya dipstick Jimmy!