75W90 vs 80W90

[beliboy32]

Hey i've got a question about the diff fluid. What effect will it have on the transfer case and front differentials if you put 80w90 instead of 75W90. I know the rear takes 80W90 which is whats confusing me. ... btw i have a 2001. The reason for the question is cost 75W90 where I live

I'm looking for some more logical approaches to this question not ....cause the manual say so....There's more then one way to skin a cat

 

[idlingmike]

If you're costs are your concern, the best deal in town is using the correct fluid.

 

[Chuckles89]

i put 80w-90 in my front diff over a year ago and it's been doing fine lol. I wouldn't risk it in the transfer case though.

 

[Cadaverous]

75w90 in both diffs and transfer case.

 

[beliboy32]

75w90 in both diffs and transfer case.

Manual says 80W90 in the rear

 

[beliboy32]

i put 80w-90 in my front diff over a year ago and it's been doing fine lol. I wouldn't risk it in the transfer case though.

Thank you makes sense

 

[beliboy32]

If you're costs are your concern, the best deal in town is using the correct fluid.

i can get a differential on a free parts day for $50 bucks at my local wreckers. its almost 50 for the fluid so no the best deal isnt.... because before that breaks i would have replaced more then difference in cost in switching fluids

 

[JWaldz]

I run premium oil (Redline Oil) in my diffs and transfer case, all 75w90. Never had any issues.

The main reason behind why most use 75w over the 80w, is that it's a lot more common. It can be found in many more brands than a 80w.

75w viscosity is better in colder conditions, but the difference between it and a 80w viscosity is so little I doubt it plays much of a factor.

You will be just fine running 75w90 and this way you wont have to keep up with different viscosity oils for your diffs and transfer case.

 

[beliboy32]

I run premium oil (Redline Oil) in my diffs and transfer case, all 75w90. Never had any issues.

The main reason behind why most use 75w over the 80w, is that it's a lot more common. It can be found in many more brands than a 80w.

75w viscosity is better in colder conditions, but the difference between it and a 80w viscosity is so little I doubt it plays much of a factor.

You will be just fine running 75w90 and this way you wont have to keep up with different viscosity oils for your diffs and transfer case.

Thank you for the explanation

 

[19963.4lsr5]

Plus 75-90 is synthetic or semi -synthetic. 80-90 is usually not.


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[Cadaverous]

I run premium oil (Redline Oil) in my diffs and transfer case, all 75w90. Never had any issues.

The main reason behind why most use 75w over the 80w, is that it's a lot more common. It can be found in many more brands than a 80w.

75w viscosity is better in colder conditions, but the difference between it and a 80w viscosity is so little I doubt it plays much of a factor.

You will be just fine running 75w90 and this way you wont have to keep up with different viscosity oils for your diffs and transfer case.

Bingo. I'm a Redline dealer, and this is 100% the case. Although we carry both.

Manual says 80W90 in the rear

Sure, but but Redline calls for 75w90. There is not a huge difference between these two oils.

 

[nobb]

75W90 is synthetic and mostly superior to 80W90, but it costs more. 75W90 has better low temperature viscosity and it is fine to run it throughout. If you're in a place that does not get very cold, there will be little advantage running 75W90 and in theory, 80W90 may even be more shear stable. However, any brand name 75W90 should have a decent base oil package so I wouldn't worry about that as long as you're changing out the fluid regularly.

I suspect the only reason Toyota spec'ed 80W90 in the rear diff is to save some money as back in the day 80W90 would have been more common.

 

[19963.4lsr5]

I put 75-140 in the rear last time. 75-90 goes everywhere else.


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[kolelt]

75-90 or 80-90. Are we really going to lose sleep over 5 difference ? Are we really going to tell the difference ?

 

[TheDurk]

75-90 or 80-90. Are we really going to lose sleep over 5 difference ? Are we really going to tell the difference ?

I tell her the truth...I can't get synthetic in the spec weight, so shut up and drink the good stuff. She said, "No problem."....hic

 

[kolelt]

I tell her the truth...I can't get synthetic in the spec weight, so shut up and drink the good stuff. She said, "No problem."....hic

Lmfao.

 

[fblainen11]

i can get a differential on a free parts day for $50 bucks at my local wreckers. its almost 50 for the fluid so no the best deal isnt.... because before that breaks i would have replaced more then difference in cost in switching fluids

Buy once cry once.

 

[Hunter89]

once the diff oil gets to operating temperature, I'm pretty sure 75w90 and 80w90 have the same viscosity. Just like engine oil, viscosity is only for cold starts. BTW the "W" in 75w90 stands for winter not weight, contrary to popular belief.

 

[csp]

Viscosity is only for cold starts??? That makes no sense. Viscosity means how thick or resistant to flow an oil is.

The first number is the viscosity at low temps and the second is the viscosity at 100 degrees Celsius, so yes, once up to temp a 75w90 is the same as an 80w90.

 

[Lindenwood]

I believe that was what he was trying to say.

I put 80w/90 in my diffs and case about 1000 miles ago because...

1) I am going to replace the fluids my next oil change to clean out the diffs and TCase.

2) I live in FL so it doesnt really get cold enough to stress about the slightly higher "cold" viscisity.

Seriously, your engine is waaay more complex and even Toyota days it is perfectly happy with either 5w-30 or 10w-30 as long as within a 120-degree environmental temperature range!

You are not going to hurt anything at all with 80w90. Other than in my engine, I prefer shorter change intervals so I am happy running cheap fluids since I like to change them relatively often (will probably go 15-20k on my future diff and tcase changes). If you like synthetics, then go synthetic because that's fine too.