2003 Expedition Eddie Bauer with 92k miles. I recently had the differential serviced at one of those Kwik Kar shops. The receipt shows that they used Golden West 75w90 synthetic. Now I find out that it should have 75w140 fluid. Should I be worried? Should I take it to a different shop and have them service it again using 75w140. I don't do any severe driving or towing.
Differential Fluid
- Thread starter GaryH
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
SafariGoneWrong
Full Access Members
I’d get 75W-140 synthetic soonest. Ford spec’d that for a reason in the 9.75 instead of what had been used in the 8.8 (75/80W-90). Maybe it’s because the 9.75’s capacity is only 4.3 pints and it’s doing more work…no axle tubes for heat transfer…I’ll stop guessing.
EngineerMike
Active Member
Definitely prudent to get it changed
Hamfisted
Full Access Members
The heavier 75w-140 gear oil was recommended for customer complaints of whining / humming from the differential when the "fuel efficient" 75w-90 was used from the factory. There was a TSB out for it.
Gear Oil Upgrade TSB 05-23-3 for Fords
.
Gear Oil Upgrade TSB 05-23-3 for Fords
.
I do have the whining/humming at certain speeds, but it's been doing that since I bought it in 2006. So I can live with it now. My concern is if the lighter weight gear oil was going to cause damage to the differential.
Vincent Vega
Full Access Members
Just swap it out. Your rear diff should have a drain plug, making the job much easier. Just drain and fill. For the front, which does not have a drain plug, you will need to suck it out. Get an air-powered vacuum (often used for bleeding brakes) (Harbor Freight or Amazon has em for like $30) and suck out the fluid through the fill cap, then refill. The Motorcraft synthetic 75-140 is available on Amazon, dealerships... Not cheap, but not worth messing around with off brand stuff. You will also need 4 oz of the limited slip additive. Your diff isn't going to scatter with the 75-90, but I suggest swapping it out soon. BTW I still use 75-90 in the front diff, with no issues, per the manual.
I changed the diff fluid in mine at 64k and this is what the magnetic drain plugs looked like. For sure, looks to me it was needed to be done much earlier. I went and refilled it with the factory recommended 75w-90 fluid from Ford but next time I’ll be going to the 140 weight oil. I have a max so it has the 9.75 rear diff and it took slightly over three quarts.
Others also mentioned the front differential only has a fill plug so you have to vacuum out the fluid. It also does not have a magnetic plug while the rear has one at the drain and fill. What I did to add one is to use a little Teflon tape to space it out since the magnetic plug is a bit thicker and bought and installed a rear drain bolt with a magnet and installed it at the front. Unfortunately, that magnet is only at the top of the fluid but better than nothing. It was only a few dollars from the Ford dealer.
Similar threads
