Will Mobil 1 5W-40 mix well with "regular" Mobil 1?

[tenderloin]

My friend has 4 qts of Mobil 1 5w30 and wants to add 1 qt Mobil 1 5W-40 to "thicken" up the oil. Any comments, problems or concerns? Chevy truck w/V8.

Thanks

 

[Ron AKA]

You would need 5 qts of 5w40 to make a significant difference in the running viscosity. No harm however in mixing in the 5w40.

 

[Triple_Se7en]

I did it twice -- one time with 5W-40 .... another time with 15W-50 in my Colorado 4X4. Even added a half-bottle of VSOT with it.

 

[TooSlick]

You'd be better off adding 1-2 quarts of their 15w-50, which uses a similar additive chemistry.

TS

 

[Vilan]

No worries. A quart of 5W40 will barely be noticeable. Even if he added a quart of 20W50 the overall mixture would probably still be within the 5W30 range, 10W30 at most.

 

[Ron AKA]

Not sure why one would want to increase the viscosity as a 5w30 oil is fine. However, the best way would be to add a can of STP if you really want the viscosity to increase. It would likely change it to about a 10w40 oil.

 

[Auto-Union]

The 5w-40 is not SuperSyn base. Mobil ok's mixing SS viscosities. Not a bad idea to mix with 15w-50 SS, but avoid mixing with the 5w-40.

 

[georgeyew]

I mixed M1 5W30 and T&SUV in my Element and the UOA results were great (you can find it in the UOA section). I wanted something a little thicker than the regular 5W30 and I think that I found my magic ticket.

 

[RF Overlord]

tenderloin, that brew will thicken the 5w30 from 11.3 cSt to 11.9 cSt...why bother?

To answer your question, I agree with Auto-Union that it's not ideal mixing the two, although it most likely is not an issue.

 

[ebaker]

The extra ZDDP, detergents, and esters from the 5w40 would probably be beneficial.