Front and Rear Diff Question
Front and Rear Diff Question
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
LOL.... That's the magic question it seems. First, what truck do you have? 250/350 with single rear wheels, or 350+ dually?
The diff for SRW gets 75w-140 syn, the front *can* get the same, according to Ford. Front was supposed to be straight 90w, IIRC. But most folks use syn 75w-90 if not the 75w-140. Personally, I would use syn 75w-90 in the front & 75w-140 in the rear for SRW trucks. For duallies, they also originally had 75w-90 in the rear, but were also apparently switched to 75w-140. I would stick to 75w-90 per Dana.
BTW, I stopped by my local Ford dealership, and asked why they changed the specs. Their answer was "Because we quit making 75w-90". So pick one and go with it, I guess. Does this help or not? LOL
The diff for SRW gets 75w-140 syn, the front *can* get the same, according to Ford. Front was supposed to be straight 90w, IIRC. But most folks use syn 75w-90 if not the 75w-140. Personally, I would use syn 75w-90 in the front & 75w-140 in the rear for SRW trucks. For duallies, they also originally had 75w-90 in the rear, but were also apparently switched to 75w-140. I would stick to 75w-90 per Dana.
BTW, I stopped by my local Ford dealership, and asked why they changed the specs. Their answer was "Because we quit making 75w-90". So pick one and go with it, I guess. Does this help or not? LOL
Laughing Gas
Joined: Dec 2005
Posts: 1,087
Likes: 189
From: Reno, NV
Front- 75W90, takes just under 3 qts
Rear- 75W140, takes about 3.5 qts
For the rear, either get the gear oil that has the friction modifier or you'll need to add some if you have a limited slip. Go with synthetic.
Rear- 75W140, takes about 3.5 qts
For the rear, either get the gear oil that has the friction modifier or you'll need to add some if you have a limited slip. Go with synthetic.
Lead Driver
Joined: Jan 2007
Posts: 6,708
Likes: 5
From: Kiowa CO
That is the critical part of this discussion.
PREMIUM SPONSOR
Joined: Feb 2009
Posts: 6,037
Likes: 73
Thread Starter
|
Junior User
Joined: Mar 2006
Posts: 53
Likes: 0
From: Firth Nebraska
Mine is a 250 SRW. I work for John Deere so i would like to put our gear lube in it cause i can get it right at work, But all we have 70-90 or 80-140 and/or 85-145 and i can get those in synthetic, any of those work?
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
Out of those choices, 70w-90 for the front, and 80w-140 for the rear. Definitely go syn, and add the FM if that fluid doesn't have it if you have a LS rear diff.
Trending Topics
Thread Starter
|
Junior User
Joined: Mar 2006
Posts: 53
Likes: 0
From: Firth Nebraska
Ok thank you all for the help! I am going to see what i can get at work tomorrow. I think i am just going to get some friction modifier for my LS rear end at an auto parts store.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post
LeoJr
1987 - 1996 F150 & Larger F-Series Trucks
6
Feb 28, 2013 05:04 PM
