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Sorry in advance for my ignorance. I’m certain this info can be found, but the more I search the more confused I become
Short of it: what diff fluids can be used for ‘94 F150 2WD with a 3.31 non-limited slip?
Longer version: I’m hoping that I’m reading my door jamb codes correctly. Based on “18” and the truck is completely stock am I correct that it’s a 3.31 non-limited slip? I learned about the easy tire spin trick but haven’t had a chance to do that. I understand I don’t need a friction modifier right? So then I’m left with 75w-90 synthetic like Valvoline bags (I love these), 80w-90 (save money with Super Tech?), or is there a TSB that says I should go 75w-140? Haha!
Again, apologies for my ignorance.
Last edited by johnstam; Mar 17, 2025 at 06:25 PM.
I just buy the lucas because it's always on the shelf. But I'm pretty sure you could get away with a handful of old grease and water from a puddle and it would be fine. Any brand oughta do it.
I just buy the lucas because it's always on the shelf. But I'm pretty sure you could get away with a handful of old grease and water from a puddle and it would be fine. Any brand oughta do it.
not quite, the water will cause rust on the bearings and gears.
As Tom mentioned, anything of those mentioned with be fine. I like the standard stuff as it has worked for many years with no complaints but you also have to go with what you can source easily.
Alright, I just tossed some old engine oil in there cuz @Truckwardo said anything works here's to hopin'! jk, I'll just start with the Walmart 80-90 because I had a bottle already, and it was really cheap. Maybe I'll change it in a few thousand miles because I know nothing about the truck's history so it's probably worth running a quicker change. Thank all 3 of you for your advice and being gracious about a dumb question.
But I'm pretty sure you could get away with a handful of old grease and water from a puddle and it would be fine.
I bought the 4wd F150 to move us across the lake, which it did just fine in 2wd. I'd checked the fluid levels in everything when I first got it-
except the front diff fill plug was buggered up, so guess what let go one snowy drive home from work on the east 520 high rise?
Slid to a stop, tried to back up, had the bright idea to put it in 2wd, which lead to some tire spinning, and then I unlocked the hubs.
And commuted in a 2wd pickup for the next 3 days.
When I pulled the drain plug, half a cup of water and 3 glops of... something brown... oozed out, followed by some silver paste.
I still haven't fixed that. I still feel like a moron for not taking the preventative effort to fix the PLUG.
t
runs whatever 'reasonable quality' national brand is on cheap at the (sometimes) friendly local auto parts store.
They (Ford Spicer and Dana) did NOT change the specs on rear axles and differentials when they switched to using synthetic fluids in them
Means it was, and still is, about gas mileage and CAFE
I run both types, depending on cost mainly, and if I am worried about fuel mileage
I believe it was 95 and up that got the expensive synthetic stuff from the factory
IMO, all oil should be synthetic, that way we can save the crude for gasoline, diesel, Kerosene, textiles, plastics et al.
Definitely understand the CAFE thing you mentioned.
So, part of my confusion is that everybody says you use almost any fluid. Haha! Forgive me again for my stupidity, but set me straight here with final clarity... All of you seem to agree that I can go to Walmart and buy any of these options: Supertech SAE 80w-90, Valvoline 75W-90 Full Synthetic, or Valvoline 75W-140 Full Synthetic. I understand each person has their preference, but I'm realizing my confusion comes because maybe these diffs just aren't all that picky about fluids?
This is what came out of my rear axle, 3.55 open differential, in 2020. I washed it all out with WD 40, and put 80/90 in it. I changed it again about 3 years later.
They'll take some abuse, not that that's my goal, and I'm not running it at the drag strip or off road racing.
A syringe like this one works good, if you don't want to pull the rear cover. I used the syringe the second time I changed my gear oil.
hahaha wow that's incredible. I plan to pull the cover and do the works on it because I know nothing about it's history! This pictures instill a whole lot of confidence in the abusability.
hahaha wow that's incredible. I plan to pull the cover and do the works on it because I know nothing about it's history! This pictures instill a whole lot of confidence in the abusability.
It is known to be the most abuse resistant part on a car. Changing the fluid every 2 years was a funny thing to add to the service manual. Just to sell fluid. Once every 100 000 miles is plenty.
here's to hopin'! jk, I'll just start with the Walmart 80-90 because I had a bottle already, and it was really cheap. Maybe I'll change it in a few thousand miles because I know nothing about the truck's history so it's probably worth running a quicker change. Thank all 3 of you for your advice and being gracious about a dumb question.
