Winter vs summer gear oil?

[Cessna_Pilot]

With winter approaching, I just changed all the fluids in my truck (2001 Tacoma 4wd). For the rear differential, the manual recommends SAE 90 above 0 deg F. For lower temps it says either SAE 80 or 80W-90.

Because I take it up to Vermont skiing almost every weekend and it can be pretty cold, I used 80W-90. Now I'm thinking that was a bad move because it is still getting up into the 50s here during the day.

Drain it now and put in 90, or don't worry about it?

 

[gathermewool]

Don't worry about it

 

[webfors]

80w90 is good year round. If you're concerned use a good quality syn in the diff and change it out every 50k or 2 years.

 

[Zaedock]

It's perfectly fine for year round. I use 80W90 in my Jeeps all year and one of them gets frequently beat on.

 

[ryan2022]

Yes the 80w90 is fine for you.

Its just as thick as a straight 90 weight, and 80w90 in general is very stout.

Gear oil is a different beast.

 

[mechtech2]

You are splitting hairs.
Your 80-90 is just fine.
I hope you put in a full synthetic - I like full synthetic lubes in trannys and rear ends.

 

[unDummy]

The NH location has short summers.
I would use a 75w90 gear oil.
Nothing wrong with the 80w90. At your next interval, consider a full synthetic.

 

[artificialist]

Leave it alone. I live in Florida and always replace SAE90 gear oil with 80w90 or 75w90 if I service a rear axle, and I have never experienced a single problem with that.

Most stores don't even sell a SAE 90 oil, so it seems like it just isn't needed anymore.

 

[pavelow]

You could run 80W90 year-round without any issues. Synthetic is better because it flows better in the cold. I run Valvoline Syn 75W90 (f) and 75W140 (r) in my Jeep Wrangler without any issues at all....regardless if it's in 100F or -30F weather. 110K miles and counting. lol

 

[Gary Allan]

Cessna_P ..you've permanently left your mark on BITOG. We now have a 6 month DCI (differential change interval). A first.

Congrats!

 

[JohnBrowning]

Why not get a 75W80 or 75W90 some places make a 70W90 or they used to.......In the end though if you use a nice synthetic properly formulated even a 140wt gear oil would do fine in the rear end! A cheap 140 would not work! So their is a lot riding on what you decide to use. Personely I would put Redline,M1 or Amsoil gear lube init and leave it alone no need to change this often it is almost stupid in how wasteful it is and how unneeded it is. usualy 2 years or 24K miles is more then often enough baring water crossing that you think might have allowed water into the gear lube.

 

[PT1]

If you look at some of the 75w90 synthetics like Amsoil, M-1, Synpower they are a bit thicker at temp than the 80w90 is. Plus they are thinner at cold temps which would serve your needs just fine.

80w90 Cst@100C = 14.5
75w90 syn Cst@100C =15.2

So you get better cold flow and a bit thicker oil at operating temp.

 

[PT1]

Originally Posted By: Gary Allan
Cessna_P ..you've permanently left your mark on BITOG. We now have a 6 month DCI (differential change interval). A first.

Congrats!

Should I get fumoto valves for my diffs & tcase?

 

[m37charlie]

Originally Posted By: PT1


Should I get fumoto valves for my diffs & tcase?

I would NOT. One will get knocked off, drain all your oil and cause a catastrophic failure.
Just use 75W90 synthetic in diffs/whatever specified in Tcase (preferably Redline version), change every 4 years or 60K miles, and don't worry any further.

Charlie