




⚙️ Gear up with Lucas Oil – where performance meets precision!
Lucas Oil 10121 75/140 Syn Gear Oil is a premium synthetic lubricant designed for high-performance and heavy-duty applications. It features a non-foaming formula that maintains lubricity at elevated temperatures, is ideal for limited slip differentials, and meets or exceeds multiple industry standards including API GL-5 and MIL-PRF 2105-E. Trusted by professionals, it reduces gear noise and extends bearing life for reliable, long-lasting drivetrain protection.

| ASIN | B000BCKWVE |
| Best Sellers Rank | 51,742 in Automotive ( See Top 100 in Automotive ) 106 in Gear Oils |
| Brand | Lucas Oil |
| Customer Reviews | 4.8 4.8 out of 5 stars (667) |
| Date First Available | 7 Aug. 2012 |
| Item Weight | 898 g |
| Item model number | LUC10121 |
| Manufacturer | Lucas Oil Products Inc |
| Manufacturer part number | LUCA10121 |
| Model | 75/140 Syn Gear Oil |
| OEM Part Number | 10121 |
| Product Dimensions | 8.38 x 8.38 x 29.85 cm; 898 g |
| Viscosity | 75W-140 |
A**Y
Good
Product was up to standards
P**Y
Good stuff
Great
J**3
Five Stars
Oil?
G**Y
quieter gearbox now
did make an improvement.thanks
P**S
Good product
I have not had to use this oil yet the gearbox was at it's max level, but it looks to be a good product and I'm very happy with my purchase
N**1
I needed to do a fluid change on the rear diff of my 2002 F150 with factory limited slip. I have never used any Lucas product before, only seen their oil additives (and I don't use additives at all, Lucas or other brands). I have read some bad reviews of Lucas gear oils, but most seem to be complaining of issues in transmissions or transfer cases, not differentials, so I figured why not try it. It meets all the specs and is cheaper than other synthetic fluids of the same viscosity (even cheaper than Supertech 75w-140 synthetic from Walmart). I did notice this fluid does not have as strong a foul odor like some gear oils do. It still smelled, but not as bad as others I have used before. I changed the fluid with no major issues and it seems to work just fine. I did add the Motorcraft XL-3 Friction Modifier to the differential. The Lucas fluid is supposed to contain Friction Modifier and it says no need to add more, but I have heard of many people having rear end chatter with the OEM Ford LS no matter what fluid is used unless the Ford friction modifier is added too, so I did it. I was having some chattering from the rear end when doing sharp turns from a stop before I changed the fluid, no issues at all after the change. I only gave it 4 stars for now since I don't know long term how this fluid holds up. If it is still good in a year, I will change it to 5 stars. As of right now, I would not hesitate to use it again. Edit 7/10/15: Well, it is a year later and nothing to report except truck is still running fine with no noise or leaks from the rear end. Seems like a solid choice for gear oil for me. Will be on the top of my list if I need more. 5 star rating now. another edit 9/16/16: well, no more updates on this fluid. I had to drain my rear diff (had to replace the anchor plate for the passenger side brake caliper, which requires removing the axle shaft and draining the fluid). I debated re-using the fluid, but decided not too. The fluid came out looking almost like it went in. Only had 10,000 miles or so on it though. I did not use more Lucas fluid for the refill, I just went with some Supertech gear oil from Walmart instead. Seems the price of the Lucas has gone up and cost as much as other name brand fluids, loosing its biggest advantage for me (low cost).
C**E
Todo correcto. Producto y envío ok. Volveré a comprar seguro. Contacto con el vendedor ok.
M**D
Did not solve my problem, noise is increasing and now I can feel hard acceleration.
A**E
Use Lucas products for many years. They always do what they made for.
R**N
Good product
Trustpilot
3 weeks ago
2 months ago