Transfer case oil 80W90 GL-5 question

Joined
Aug 1, 2017
Messages
2,642
Location
WA
I have a 2005 Hyundai Tuscon MPFI 2.7L V6 4WD Manual spec for Trasfer case oil is: API GL-5 SAE 80W90 (Shell Spirax AX Equivalent). 0.8 Quart that's all it says Same spec also for Rear Axle ... btw, it says rear axle and not rear differential ?? I bought a quart of Valvoline 80W90 GL-5 High Performance ... The back of the valvoline bottle says: ... For non-synchronized manual transmission when GL-4 is specified and for hypoid differential when GL-5 is specified ... Limited slip differential top-off only. Came home and found out I had a little left-over from last time I changed the oil ... I think about 40K miles ago and may be 5-6 years ... My last change was with: Castrol Axle Limited Slip 80W-90 Gear Oil, 1 Quart Recommended for service fill of all limited slip differentials in passenger cars and Light trucks calling for SAE 80W-90 and API Service GL-5 specifications is the valvoline I bought this time more suitable than the limited slip castrol running in it for the past 40K miles? The car didn't blow up but which oil is more suitable? I need to read Shell AX spec and see what it is.
 
Joined
Nov 12, 2019
Messages
514
Location
Upstate
As long as you have an open differential, the Valvoline will be fine. If it starts chattering after you change it, that probably means it's a limited slip, and you'll want to add a bottle of limited slip lube. The Valvoline's not necessarily more suitable, just the Castrol had additive you may not have needed. Dino based GL-5 gear oil isn't anything special, and you can safely mix the Valvoline and Castrol.
 

Sam_Julier

$50 Site Donor 2022
Joined
May 22, 2012
Messages
1,144
Location
Connecticut
Molacule has forgotten more about this than most people on this site. I would ask him for his recommendation. My .02 is that any 80W90 GL-5 that meets SAE J2360 is fine. But it also depends on how often you plan to change the fluid and the difficulty of changing it. The Amsoil 80W90 may be a better choice. Sam
 
Joined
May 27, 2008
Messages
5,048
Location
Parts Unknown
The axle contains the differential, which in the Tucson is a open differential, not limited slip. But even with the Friction Modifiers in the Limited Slip fluid, you can still use it in an open differential. The AWD system is your typical majority FWD-until slip (predicted or detected) system. Open front, open rear, multiplate clutch coupling at the rear.
 

OilUzer

Thread starter
Joined
Aug 1, 2017
Messages
2,642
Location
WA
Thank you all. based on what you all saying, the limited slip friction modifier was not needed but also not harmful ... However as explained by @UG_Passat and with further investigation, the car seems to be open differential and not limited slip. It also has a 4WD-Lock button for %50/50 under 30 or so mph ... we have owned the car new since 2005 and I still didn't know that. I'm a fast learner grin2 by next oil change, I may forget again and ask the same question. lol seems like I could use the Valvoline but I like the Amsoil idea. It's only 0.8 quart ...
 

OilUzer

Thread starter
Joined
Aug 1, 2017
Messages
2,642
Location
WA
few more questions: If a slip is not detected or predicated and assuming the car stays in Front Wheel Drive (FWD) mode only ... -1- Does this mean the transfer case is not doing any transferring i.e. rear wheels are not engaged at all and turning freely? -2- Would the drive shaft (connecting front xfr case to rear axle) rotate at all under normal FWD operation? -3- What's going on inside the transfer case if the rear wheels are never engaged? iirc, last time I changed the transfer case oil, it looked pretty clean/good! hypothetically speaking, If slip was never to be detected, can transfer case be empty with no oil? I know this may get very involved but a simple yes/no is appreciated if you don't have time ... Meanwhile I will study the subject when I get some free time.
 
Joined
Sep 1, 2015
Messages
2,879
Location
Malaysia
Originally Posted by OilUzer
few more questions: If a slip is not detected or predicated and assuming the car stays in Front Wheel Drive (FWD) mode only ... -1- Does this mean the transfer case is not doing any transferring i.e. rear wheels are not engaged at all and turning freely?
In a typical transfer case power distribution as I know it : Yes, no transfer of torque/power from within the transfer case/transmission systems to the rear axle system .
Quote
-2- Would the drive shaft (connecting front xfr case to rear axle) rotate at all under normal FWD operation?
The transfer case output shaft (to rear axle system) is rotating under normal FWD mood , but receiving no power/torque transfer from within transfer case/transmission systems . The transfer case output shaft (to rear axle system) is being driven by the centre propeller shaft ,which in turn is driven by the rear differential unit, which in turn is driven by rear tyres and half shafts system , in a typical FWD mood .
Quote
-3- What's going on inside the transfer case if the rear wheels are never engaged? iirc, last time I changed the transfer case oil, it looked pretty clean/good!
The input shaft into transfer case is rotating and being driven by auto/manual transmission . But its output shaft (to rear axle system) is not receiving torque/power transfer from transfer case/transmission systems . This output shaft is being driven though, receiving energy from the rear axle system .
Quote
-hypothetically speaking, If slip was never to be detected, can transfer case be empty with no oil? I know this may get very involved but a simple yes/no is appreciated if you don't have time ... Meanwhile I will study the subject when I get some free time.
No, as the input shaft to the transfer case is rotating and being driven by transmission and deliver torque/power to the front axle system, in a FWD mood , whilst no torque/power is being transfered to the rear axle system . Just my 2 cents . Edit:grammar
 
Last edited:
Top