whats the difference in gear oil

[mean machine]

hello i have read in a manual to use gl4 gear oil in the fm146 all i can find is gl5 whats the difference right now i have walmart 75w90 synblend in it and it seems ok but what do you guys think ??

 

[Die.Fledermaus]

Its gear oil, you have a gear box.
The improvements/updates made to oil before calling it GL-5 supersede the standards of calling it GL-4

 

[BRUTUS_T_HOG]

GL-5 is better rated than GL-4. Newer, better spec.

 

[1986fordranger]

yup, GL4 was up to spec for around 1988 to 1989, alot has changed for the better since then, just stick with GL5 and you'll be fine

 

[a31ford]

Just a note about cold weather.... (MINUS 30 stuff, that's -30)

I'm using synthetic 50w heavy truck transmission oil in my FM 146, 75-90 is simply too thick at this type of cold, if you let the clutch out, even in Neutral, the truck will try to move forward (the oil is so thick), it (even on the highway after 1/2 an hour) is so thick that sitting at a light, again will move the truck forward in neutral

Just bought full synthetic 75-90 for both diff's (since I'm working on the front one anyhow ).(dam center u joint in the front end).

Greg

 

[EMB1230]

75-90 is simply too thick at this type of cold, if you let the clutch out, even in Neutral, the truck will try to move forward (the oil is so thick)

My 87 with a TK5 does this when I first start it. 5-10 min or so, it's fine.

 

[EMB1230]

we are finally above freezing for this first time since who knows when. Sure enough, my 87 didn't try to move in N today!

 

[mean machine]

well i was asking cause i read somewhere some gear oil will eat the brass rings in the tranny and regular 80/90 doesnt say anything about it the synblend walmart sells says nonfoaming and noncroosive to brass parts thats one reason i got it and i havent had a problem with it creeping when cold its just stiff to shift for a bit and when its at like -17 like it was last week it will stall the engine if you let clutch out in N at first lol till it warms up i usually put the t case in N and put trans in first or second to warm up for a few its easier to spin the t case in netural when cold then to try and turn the gears in the trans with the gearoil when its -17 or so lol