Mixing 75W-90 and 75W-140 to form 75W-110 Viscosity?

[CarbonSteel]

I have ran Amsoil Severe Gear for more than a decade in 75W-110 (front) and 75W-140 (rear), but recent obtained quite a bit of Valvoline 75W-90 and 75W-140 and was thinking of mixing it 45/55 (90/140) to get a 21.0 cSt viscosity. Since both oils are Valvoline Full Synthetic, I do not expect any issues, but thought I would bounce it off you gals and guys.

Thoughts?

 

[Kuato]

Opinion: Roughly correct, mix away.

Fact: I recently sent in a 50/50 mix of 5w-20 and 20w-50. Came back as a 40 by one test(barely) and a thick 30 on the other, so a guesstimate by average of 35 works, and would expect similar with your mix.

 

[CarbonSteel]

Opinion: Roughly correct, mix away.

Fact: I recently sent in a 50/50 mix of 5w-20 and 20w-50. Came back as a 40 by one test(barely) and a thick 30 on the other, so a guesstimate by average of 35 works, and would expect similar with your mix.

I did something similar with Rotella Gas Truck with 0W-20 and 5W-30 in a 60/40 mix which should have resulted in a 9.64 cSt according to the Widman calculator. The VOA of the mix (measured in beakers) was 9.6, so it should be close for the gear oil too.

 

[JavierH19]

it's a rough estimate since you'd really need the exact kv100 viscosity figures of both to input into a viscosity calculator like Widman's. But don't bother just mix both and chuck in it doesn't matter that much unless you wanna waste time.

 

[CarbonSteel]

it's a rough estimate since you'd really need the exact kv100 viscosity figures of both to input into a viscosity calculator like Widman's. But don't bother just mix both and chuck in it doesn't matter that much unless you wanna waste time.

I just took them from the PDS of both oil (the Rotella Gas Truck and the Valvoline gear oil). It is spot on based upon the results of the VOA for the RGT.

 

[IndyFan]

I have ran Amsoil Severe Gear for more than a decade in 75W-110 (front) and 75W-140 (rear), but recent obtained quite a bit of Valvoline 75W-90 and 75W-140 and was thinking of mixing it 45/55 (90/140) to get a 21.0 cSt viscosity. Since both oils are Valvoline Full Synthetic, I do not expect any issues, but thought I would bounce it off you gals and guys.

Thoughts?

Why not just the 90 in the front and 140 in the rear as you've done, unless you have a bunch more 90 than 140? Or, put the first full quart of 90 in the front with the 140 as top off and do the opposite for the rear? That'd make it a little lighter in the front and a little heavier in the rear.

 

[ripcord]

Why not just the 90 in the front and 140 in the rear as you've done, unless you have a bunch more 90 than 140? Or, put the first full quart of 90 in the front with the 140 as top off and do the opposite for the rear? That'd make it a little lighter in the front and a little heavier in the rear.

HAHAHA!! Must resist! Must resist!

 

[CarbonSteel]

Why not just the 90 in the front and 140 in the rear as you've done, unless you have a bunch more 90 than 140? Or, put the first full quart of 90 in the front with the 140 as top off and do the opposite for the rear? That'd make it a little lighter in the front and a little heavier in the rear.

I want the extra protection of 75W-110. I am currently running 85W-140 in both until they are well broken in (it takes a WHILE in these iron shedding Advanteks) and once that is done I will switch to synthetic.