Inadvertently put 5 qts. of Mobil 1 5w-20 and 2 qts. of Mobil 1 5w-30 during oil change last week. I am leaning toward replacing the 5w-20 with the recommended 5w-30 oil with another oil change ASAP. Am I being too cautious ??
I live in an area where temps rarely are above 75.
Interested in opinions.
Thanks in advance.

 

I would not risk having an engine failure (even though I don't think you will) or damage it. I would do it again. It is only $50 after all.

 

You put in 7 quarts of oil in what engine?

 

My vehicle is a 2017 C7, 7M Stingray (non Z51) with 7 qt. wet sump, 7000 miles.

 

7qts is right.

I would change it out.

\db2

 

The Silverado can use down to 0W20 Dexos and survive, so frankly I think you're fine, especially if things aren't hot.

The cautious and correct answer is "change it out for the recommended oil". The reality is I wouldn't track it like that, but you're likely fine.

 

Thanks for the replies... I agree with you all, the prudent thing is to replace all the oil with Mobil 1 5w-30 which I did. I shall sleep better tonight.

 

Do you ever look at the oil temp?

If it stays below 250ºF then you will be as "good to go" as xxW-30 is at 280ºF.

 

^^ this. It would have been fine unless you really beat on it on the street or track..

 

Temps rarely go above 220 and mostly hover in 190-210 area. But it's a moot point as the oil was changed to 7 qts. Mobil1 5w-30

 

The thing most people fail to understand about oil is that::

A) it is viscosity that keeps metal from touching metal
and
B) viscosity changes with temperature
and
C) oil grade-weight does not
and
D) they only put grade-weight on the cans and in the manual.

xxW-30 is a grade-weight classification.
14 centiStokes is a kinematic viscosity (operating viscosity)
3.5 centiPascals is a dynamic viscosity (HTHS viscosity)

The difference between kinematic viscosity and dynamic viscosity is the density of the oil.

The flow rate through a journal bearing is dependent only on the kinematic viscosity.

The amount of oil thrown off the crankshaft at high RPMs is dependent on the kinematic viscosity and the density of the oil (thus dynamic viscosity.) Higher density oil gets thrown off as a slightly slower rate than lower density oils.

If a given oil performs well at temperature T, then the same brand oil at one grade-weight lower will perform equally well at T-30ºF, and the same brand oil one grade-weight higher will perform equally well at T+30ºF.

So we have the standard oil xxW-30 that GM thinks performs (i.e., protects) well at up to 270ºF. This means if you start running at loads where you are dumping crap-loads of heat into the oil (think track use) and the oil gets up into the 300ºF range, the xxW-50 oil GM recommends for track use still has margin at 300ºF (about 30ºF margin) and protects well at these elevated temps and track loads.

Your situation is the reverse, so watch the oil temps and if your oil stays 30ºF lower than 270ºF, then the xxW-20 oil is not doing your engine any harm.