75W90 or 75W110

Status
Not open for further replies.
M

mobilaltima

Joined
Feb 3, 2011
Messages
1,426
Location
Golden Meadow, LA
I had posted awhile back about using amsoil Severe Gear 75W90 in the Ranger, which yall all said would be fine, but it got me thinking would I be better off using 75W110? I might try Redline gear oil next time.Last week I changed my axle bearings and seals with the help of a friend, which was easier than i thought. filled it up with Amsoil 75W90, and ill run this for the time being. The reason I asked about the 75W110 is that most of the time spent driving this truck, which is my daily driver, is a speeds of 60-70 mph, rpms between 2200-2600. Although I did talk with someone at Amsoil and they said I would see a fuel mileage due to the thicker oil, and less heat dissipation. I dont tow anything at all, I shift in every gear around 2500-2800 rpm and the fastest I go is 70. So what do you guys recommend, and what kind of interval should go with? Amsoil states 100k but I dont feel comfortable with that. Also how often should I change out the Pennzoil Synchromesh in the 5 speed? Last question, how hard is it to change u-joints on the driveshaft? Mines are not bad but I cant get the grease gun on the fitting and for peace of mind, I figured I'd change them.
 
Last edited:
The 75-W90 is fine for what you do. As for the u-joints, they are easy with the right tools. Why not just change the grease fitting and keep the u joint?
 
You are better off with 75W110 (with higher MOFT film thickness) if you are for components longevity and drive like a teenage.
 
75W-110 is the viscosity that 75W-90 used to be before the J300 charts were updated. I have used 75W-110 everywhere that 75W-90 is specified with no issues whatsoever.
 
Originally Posted By: mobilaltima
I cant get the grease gun on the fitting and for peace of mind, I figured I'd change them.


Get a different gun nozzle of extended grease fittings.
 
2015 PSD, I remember you mentioning that awhile back. So what you are saying is, 75W90 used to be thicker and is now thinner? The bottles of severe gear 75W90 I have are made in 2011. Is 75W110 a fairly new viscosity? I think I will go with Redline 75W110 next time I change it out, how long do yall recommend going on Redline?
 
Originally Posted By: mobilaltima
2015 PSD, I remember you mentioning that awhile back. So what you are saying is, 75W90 used to be thicker and is now thinner?


x2

Also, does switching to a thicker gear oil in a high mileage differential make sense as far as added protection?
 
What happened was SAE split the 90 and 140 grades in half in...2001? Mightve been like '03 or '04 I dont remember. It was at least 10 years ago if not longer.
Anyway, the bottom half of the 90 scale remained as 90, and the top half was designated as 110. The same happened to 140 with the top half becoming 250 grade.
 
Last edited:
I would say your in the moderate to easy range and the 75w90 is just right. If you don't tow all the time and just drive around there' no need for a heavier gear oil.
 
Originally Posted By: Colt45ws
What happened was SAE split the 90 and 140 grades in half in...2001? Mightve been like '03 or '04 I dont remember. It was at least 10 years ago if not longer.
Anyway, the bottom half of the 90 scale remained as 90, and the top half was designated as 110. The same happened to 140 with the top half becoming 250 grade.


Thanks.
 
What I'd wonder is would the thicker gear oil cause any drag? If your truck specs a 90 on the high end would a 110 cause any harm to the diff? I've read where people have "burned up" (their words not mine) diffs by going to a thicker than spec'd gear oil. I'm thinking it was on a Camaro forum?
 
Thicker gear oil definitely causes more drag. If you have a way of measuring temperature of the gear oil, it can raise the temperature by 5-10F by stepping up a grade.
The best way to check if you need thicker oil, is to measure the temperature of the gear oil in typical use and if, say you have 90 grade, and you are running 190F, then you are good.
If the temperature was say 230F, stepping up a grade might raise it by 5F, but the oil is still thicker than the 90 grade was at 230F thus giving more protection.
 
Originally Posted By: Jetronic
temperature can even drop going up a grade, if the thinner one was too thin.

Correct, I meant to add that. If the thinner oil wasn't keeping the gear apart under load, then the friction generated would be more than the thicker oil, thus lowering the temp.
 
Very first time years ago I changed my rear diff oil,I tried 75W140 (thinking thicker was better) when my car specs 80W90. Felt like I was pulling a fully loaded trailer and the it made the diff "hum". I drained it and refilled with spec 80W90 and all was good again. I'm always afraid of going thicker than spec in a rear diff.
 
Originally Posted By: aquariuscsm
Very first time years ago I changed my rear diff oil,I tried 75W140 (thinking thicker was better) when my car specs 80W90. Felt like I was pulling a fully loaded trailer and the it made the diff "hum". I drained it and refilled with spec 80W90 and all was good again. I'm always afraid of going thicker than spec in a rear diff.

I'm using Pennzoil syn 75w-140 now in the diff which calls for a 90. I can't tell any difference between it and the RP 75w-90 that was in previously, about 5 years now. Only reason I put it in instead of 90 was it was nearly free.
 
I have a friend with a Snap On temp gun that I can use, would that be the best way to get an accurate temp? I have a 44 mile one way drive tomorrow, diff should be nice and hot by the time I reach my destination
 
Status
Not open for further replies.

Similar threads

B
Amsoil Severe Gear+Valvoline Synpower 75w90
Replies
1
Views
310
Bowtieluvr
B
Mustang Diff acting up AGAIN
2
Replies
21
Views
1K
alcyon
M
Amsoil 80W90 in place of Toyota 75W85 LX Gear Oil
Replies
16
Views
842
slacktide_bitog
C
Did Amsoil changed Ingredients ?
Replies
12
Views
1K
demarpaint
P
Finding vibration in front wheel well?
Replies
19
Views
838
ps2cho
Back
Top