75w-140 accidental fill

Ok here’s what happened. Picked up two squeeze bags of Valvoline

$26 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90, or so I thought for a first time front differential change, after I did my oil & filter. First bag was the 75w-90, second bag after adding it I found out was a 75w-140.
Is this bad? Should I drain and fill again now or wait till this fall. There is 26,000 on the Tacoma, a 2021 SR5. So 2/3 of the fill is 75w-90, the other being the 140.
Both bags look exactly the same except for the label.
What say you Tacoma world?

 

Do it right brother.

 

I’ve been running 75/140 for 12 years, now. I think you’re fine and…

 

Don't worry about it. it's fine. Your differential will never know the difference.

 

Is fine

 

The only reason I’d change it, is because it’s still under warranty.
Should you need to make a warranty claim on the front differential, they have a reason to fight you.

BTW. Although rare, the thicker fluid can travel up and out the front differential vent.

If you weren’t still under warranty, I would run it.
I’m running 85w-140 in my front.

 

I'd leave it, the 75w is the important bit and its the same for both.

My problem lies with thick winter ratings.

 

Since this is not my truck, I say leave it. But, if it were mine I’d change it, but I would have no qualms getting SuperTech syn fluid for the front. Consider the experience an expensive diff fluid flush.

 

I think I’ll run it for the next few days and change it. I replaced the plugs with Lexus versions. Also used a T55 torx bit, the 10 mm was wobbly, the torx really gripped the inside edges well. Could have re used them, but were in real tight.

 

10MM Allen fits just fine in there. T55 might strip the Allen head.

 

…right…

So, drain and refill is what I would do.

 

Same brand so the additives won't work against each other. 75W means viscosity when cold will be the same. Viscosity at operating temps (when in 4WD) will be somewhere between 90-weight and 140-weight oil. No real drawbacks to 75W140. In fact that's what I use in the front diff of my 4Runner.

Why were you changing front diff oil anyway? Truck is 2 years old with only 26k. You aren't due by mileage or calendar time.

 

I highly, highly doubt this will cause any issues. Plenty of people run 75w-140. I would not worry about it at all.

 

You’re essentially running 75w115 now. No big deal

 

^^^^ this ^^^^

 

If it were a transfer case mistake, I'd change the fluid out, but being the front diff which doesn't get used as often, this won't make any difference to the trucks operation. Its only to you.

 

The initial panic is over, thanks to everyone for the feedback. I will pass on changing it for now, before the winter I’ll consider doing a drain and fill.
The reason for the change at that mileage I was doing and oil change, on the ramps it was easier to break loose those plugs. I filled it on level ground. Condition of the fluid was a gray silver color, the magnet had that metallic paste. Normal for a first change.

 

It’s fine Just leave it. Won’t hurt anything.

 

I concur that it won't do anything bad to the gearbox to run your blended oil stew. But I came out of the nuclear power world where everything (and I mean everything!) Is done to spec.

So this would haunt me in my dreams so I personally would have corrected the fuck up right then and there.

 

It will not make a lick of difference. They'll just mix and average out.

That said, the folks who say that beause it's 75W, they will both be the same when cold....that is not correct.

Valvoline full synthetic pouch viscosity details:

$26 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90
40 Celsius - 92.5 cSt
100 Celsius - 15.6 cSt

75W-140
40 Celsius - 184 cSt
100 Celsius - 27 cSt

And just for extra information:

Valvoline 85W-140
40 Celsius - 370 cSt
100 Celsius - 28 cSt

The winter rating is highly misunderstood. The above fluids are both 75W yet one is twice as thick as the other. It is not correct that just because the rating is 75W, that the gear oil will be "like a 75 weight" in the cold. It is pretty much impossible to come up with a fluid that is a 140 weight when warm but flows exactly the same when cold as a 90 weight. All the first number really can tell you is that it will flow a bit quicker comparatively to the same viscosity oil with a higher winter rating. For example, 75W-140 will always flow a bit better than 85W-140. The number does not mean that 75W-90 will flow the same as 75W-140 just because they both start with 75.

You can see above that the 75W-140 and 85W-140 are very different when cold, but right at the same thickness warm, as explained above.

None of it will make any difference in the diff, no need to drain and refill again, I just wanted to correct that.