Can I Use 75W-140 Instead of 75W-90 Gear Oil?

Oils & Fluids
1

I’m in a bit of a conundrum and seeking advice on gear oil. I usually stick with 75W-90 for my truck, especially since I do a lot of towing. However, I recently came across a jug of 75W-140 and I’m wondering if it would be a suitable substitute?

Key Considerations:

  • Viscosity Differences: The main difference between the two is thickness. 75W-140 is thicker, which might provide better protection in certain conditions. But I’m concerned about differences in performance, especially under high temperatures.
  • Temperature Handling: Warm climates and heavy towing can put a strain on gear oil. I’ve read that thicker oils can handle heat better, but will it also cause any issues in cold starts?
  • Differentials: I’ve habitually used 75W-90 in my differential, but I’ve heard mixed opinions about switching to the thicker 75W-140. Could this lead to overheating or affect the diff performance?

Questions:

  1. Has anyone made this switch? What were your results? Did you notice any performance changes?
  2. What about compatibility? Are there any risks or possible drawbacks I should be aware of?
  3. Is there any situation where using 75W-140 would be more beneficial? Like, should it be limited to extreme conditions, or is it safe in average driving?

I’d really appreciate any insights, personal experiences, or expert advice on this topic. Thanks!

2

The difference between 75W-140 and 75W-90 is significant. The ‘W’ stands for winter, indicating how the oil flows at lower temperatures. The higher the second number, the thicker the oil when warm. 75W-140 is thicker and might not perform well if your vehicle is designed for 75W-90.

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3

Thanks for the explanation, kchambers! I was wondering if using 75W-140 could actually cause any damage to my transmission.

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4

Good question, paigecruz! Using a thicker oil than recommended can lead to issues such as increased wear, overheating, and fluid starvation in specific areas of the gear assembly. Stick with the manufacturer’s recommendation for the best results.

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5

I’ve always found viscosity ratings confusing. If 75W-140 is made for hotter conditions, could there be situations where it’s actually beneficial?

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6

That’s a valid point! In extreme heat, 75W-140 might offer more protection, but you have to consider your typical driving conditions first.

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7

I use 75W-140 in my truck, and it’s been great! However, it’s crucial to ensure your vehicle’s components can handle it. Always check the manual.

8

If your vehicle is designed for 75W-90 and you switch to 75W-140, you might notice sluggish performance in colder weather. Keep that in mind!

9

That’s exactly what I’m worried about. I want to ensure I’m not risking my gearbox.

10

It’s always best to err on the side of caution, especially with gear oils. Thicker oils can create extra pressure, which may lead to leaks or failures.

11

So true! I think 75W-140 has its place, but not in every vehicle. Checking compatibility is key!

12

Wouldn’t it be funny if your car just rebelled and refused to drive if you tried 75W-140? Just a thought, but I wouldn’t test it out!

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13

Haha! That would definitely be a scene! But seriously, I really want to avoid any unexpected breakdowns.

14

Just because 75W-140 may work in some cases doesn’t mean it’s a good choice for every scenario. Reflect on your usual driving conditions and make an informed choice.

15

Exactly! It’s about understanding what your vehicle needs rather than just grabbing what’s available at the store.

16

Using 75W-140 instead of 75W-90 can lead to increased gear wear in applications where lighter oil is specified. The higher viscosity may not flow as well, especially in cold temperatures.

17

That’s a good point! It’s crucial to consider the manufacturer’s recommendations before making a change.

18

In my experience, using 75W-140 in a compatible gearbox meant less noise, but I did notice it ran hotter. Keep an eye on the temperature if you go this route!

19

That’s interesting! I hadn’t thought about noise levels. I guess it really depends on the application.

20

While 75W-140 might seem like a stronger option, be cautious. It could increase friction in some systems, possibly leading to premature failure if it’s not compatible.