(approx) 1 Hour
Simple installation for anyone.
- Customer Submitted:
- How to Install Gear Oil in your 1979-2014 Mustang
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Royal Purple Max 75W-90 Gear Oil is a good choice for any Mustang owner who's picking up a new set of rear gears and wants to make sure that they're picking up a reputable, reliable lubrication. One quart of this Royal Purple Grade runs at just about the $16 mark and applying the new gear oil gets one of the three wrenches on our difficulty meter depending on your method of installation, which I'll explain in just a little bit. Now, there are some factors that come into play when picking out your new gear oil, but in order for you to first choose your oil, you'll need to understand their grades because it is crucial in making sure that the gears mesh properly and turn smoothly. Now, this one here is graded at, again, 75W-90. The grading system is measuring the viscosity of the oil, which is a measurement of the thickness of a liquid. Now, the larger the number, the more viscous or thick the oil is. You'd want thicker oil if your car is under heavy weight or load, if you've got a heavier foot and really beat on it, or if you've got big, slow, rougher gears. You'd want a thinner oil if you're running small, fast, and light gears.When you upgrade gears to something like that, or if you're just doing some routine maintenance, the 75W-90 comes in handy. It may vary depending on your new gear's manufacturer recommendations and what would be best for your application so, make sure you're doing a little research into what oil works best for you. Now, this one here from Royal Purple is a multigrade since you're seeing two numbers there, the 75W being the first and the 90 being the second grade. The W after the 75 refers to its winter viscosity grading or rating, meaning it's certified and tested at 32 degrees Fahrenheit. The 90 without the W refers to its heat rating with a certified testing at 212 degrees. A multigrade oil like this doesn't need to be changed out for the different climates it may be exposed to.If you're looking for a grade like this one here, it comes in right around 16 bucks a quart. You want to be sure to learn how many quarts your Mustang needs as it can vary depending on the generation and package. Anytime you're changing gears, you'll need new gear oil, so the installation is pretty involved. Applying the gear oil itself isn't hard, but it really depends on your method. If you're not actually changing your rear gears, but just need to change the oil, you can pick up a gear oil pump and tubing in some cases and it'll get one out of three wrenches on our difficult meter. However, if you're completely changing your rear gears, the process is on the opposite side of the spectrum, getting three out of three wrenches on our difficulty meter because you're completely disassembling the differential when applying that new oil. With that said, the installation can vary from one hour to several. That's going to wrap it up here, so if you're in need of new gear oil and you're leaning on the side of a 75W-90 Royal Purple Max gear oil, you can grab them right here at americanmuscle.com.
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February 19, 2020
No problems. I am not a chemical engineer but everything works as it should.Helpful (0)
February 03, 2020
Royal Purple is the best product for your car needs.Helpful (0)
December 29, 2019
The royal purple gear lube is yet another find product that you come to expect from the royal purple manufacturesHelpful (1)
August 12, 2019
Worked great whent to ace to get plastic tuneing to help put it in the diff. Works great.Helpful (0)
August 11, 2019
Better than conventional oil
Royal Purple Max Gear Oil reduces drivetrain power loss to the rear wheels by reducing friction and heat compared to conventional oils. You can feel the difference!Helpful (1)
July 24, 2019
Royal purple gear lube
Great lubricant. My choice for any car or truck. I've used it in several mustangs now.Helpful (0)
July 22, 2019
Royal purple max gear oil
The best oil on the market.worked great in my mustang rear endHelpful (0)
July 09, 2019
Its gear oil I dont think there is much else to say.Helpful (0)
July 07, 2019
Put this in my transmission, helped it out. Will likely use again.Helpful (2)
June 12, 2019
Excellent product. Used in my transmission for easier shifting and in rear end for protection and quiet.Helpful (0)
going to change my diff to a lsd with 4.10 gears, i have an 08 v6 wondering what the difference between the 75w90 75w140 gear oil which would be recommended
The differences in the Royal Purple Max Gear Gear Oil, 75w90 and 75w140 would be the viscosity of the oil throughout a temperature range. For moderate driving applications, 75w90 would be best, however, if the vehicle is driven in more extreme driving conditions, the 75w140 would be best for that application. If you are using the vehicle for a particular application, please give us a call and we would be happy to recommend a weight which would be best suitable for your application.
One of your staff's comments says to use the friction modifier with Royal Purple. But Royal Purple says the friction modifier is in it already and is not needed. So what is the correct answer ?
Even though the Royal Purple gear oil does include some friction modifier, we still recommend using the ford friction modifier for better performance but you can definitely just use the Royal Purple gear oil alone.
For 6th gen with Torsen 3.73 the owners manual list 1.5 liters and like 3 oz of friction modifier as capacity. Why are 3 quarts needed?
Hello! From my understanding it does vary slightly, but its about 2 quarts of gear oil and a bottle of friction modifier which is about 4 oz and you should be good.
Which is the recommended oil for daily driving and no track or drag use, 75w90 or 85w140? What weight is the factory fill?
It depends on the year and model Mustang you have, you should have your answer in your owners manual or by contacting and speaking with your dealership directly.
I ordered and received my order of 1 qt., not realizing it was only a qt. bottle. When I checked the quantity needed I saw it required 4.25 pints, but the manual also say 75W-140. Your site said this was the correct lube for the car when I ordered it. What do you recommend? 2008 Mustang GT/CS
The Royal Purple Max Gear 75w90 Gear Oil will improve shift quality, especially in colder weather. The primary benefit is reduction of friction and wear.
Three (3) quarts of gear oil are required to fill a 8.8" Ford rear end.
If you are changing gears or even adding new gear oil, it is always a good idea to add friction modifier to help the performance of the gears.
This Royal Purple Max Gear 75w90 Gear Oil is meant for your rear differential, and should NOT be used in your transmission.
yes will need 3 the differance in size does not reduce capacity by one quart
(approx) 1 Hour
Simple installation for anyone.
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