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Royal Purple Max Gear 75w90 Gear Oil

Market Price $19.99 You Save 19% ($3.86)
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  • Item 45003

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    Features, Video & Details

    • Fully Synthetic
    • Friction Modifier Included
    • Protects Against Wear
    • Reduces Gear Whine
    • 75w90 Weight
    • 8.8" Ford Rear Ends Require 3 Quarts
    • For 1979 to 2017 Mustangs

    Review & Installation Video

    Review & Install Video

    Pure Performance. Maximize performance from your Mustang's drivetrain with Royal Purple Max Gear oil. This fully synthetic oil is the perfect complement to new gears, lubricating better and ensuring your differential keeps working its best whether it has gone a thousand miles or a hundred thousand.

    Protect Your Investment. Made with Royal Purple's innovative Synslide® additive, Max Gear oil is perfect for upgrades or routine service. It's the gear oil of choice for greater wear protection and lower temperatures for every car, from daily drivers to track-day toys. It prevents corrosion and meets all warranty requirements, so adding Royal Purple Max Gear oil is great for peace of mind when it comes to your Pony.

    Includes Friction Modifier. Unlike other oils, all viscosities of Max-Gear® are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary.

    Application. Royal Purple Max Gear 75w90 weight oil is recommended for use in 1979 to 2017 Mustangs and is compatible with other oils. Three (3) quarts of gear oil are required to fill a 8.8" Ford rear end.

    Fitment: 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Details

    MPN# 1300

    CA Residents: WARNING: Cancer and Reproductive Harm -

    What's in the Box
    • (1) one quart bottle
    Installation Info
    Tech Specs
    Will it fit my Mustang?
    • Boss 302 - 12, 13
    • Bullitt - 01, 08, 09, 19
    • Cobra - 93, 94, 95, 96, 97, 98, 99, 01, 03, 04
    • Cobra R - 93, 95, 00
    • EcoBoost - 15, 16, 17, 18, 19
    • GT - 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19
    • GT350 - 15, 16, 17, 18, 19
    • GT350R - 15, 16, 17, 18, 19
    • GT500 - 07, 08, 09, 10, 11, 12, 13, 14
    • LX - 87, 88, 89, 90, 91, 92, 93
    • Mach 1 - 03, 04
    • Other - 79, 80, 81, 82, 83, 84, 85, 86
    • V6 - 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17

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    Questions & Answers (9)

    5 Top Rated Questions

    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. 

    Helpful (1)

    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.

    Helpful (1)

    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.

    Helpful (1)

    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

    Will this bottle of solution make shifting a manual tremec (2010) 5 speed shift smoother? Does it affect the shifting in a good way?

    • 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.

    Helpful (0)
    Post Your Question
    4 More Questions
    I'm confused, so to clarify when changing Gear oil do I need 2 or 3 quarts? 1 answer
    On the bottle and in the part description it states - Friction modifiers included, no additional additives are necessary. Is the Ford modifier really required? 1 answer
    How good will this work for the MT82 transmissions. 1 answer
    7.5? 3 quarts are needed for the 8.8 but what about us v6ers. i'd get three to be safe but if i could save an extra 17 bucks that would be nice too. what do you think? 2 answers

    Recommended For You

    Customer Reviews (63) Write a Review

    Overall Rating 4.8

    out of 5 stars

    Installation Time:Less than 1 Hour

    Installation Cost:0-$100

    • Performance Gain 4.5625 4.6
    • Fit 4.8125 4.8

    • 5/5

      Installation Time: Less than 1 Hour

      March 18, 2019

      Royal Purple is quality you can trust

      If you race or just want your gears to last then use Royale purple gear lube. Quality at its best.


      Year: 2013 Submodel: GT

      Helpful (0)

    • 5/5

      Installation Time: Less than 1 Hour

      November 26, 2018




      Year: 2014 Submodel: V6

      Helpful (1)

    • 5/5

      November 03, 2018

      Best stuff

      Going in tomorrow It's gear oil change time and transmission fluid change time...


      Year: 2016 Submodel: V6

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      October 29, 2018

      Best gear oil

      This is by far the best gear oil on the market. Also cheaper than going to local parts store.


      Year: 1999 Submodel: Cobra

      Helpful (2)

    • 4/5

      October 22, 2018


      It was time to change the diff fluid - I went with Royal Purple mainly due to other reviews. Install was easy. I have not noticed any performance increase, etc. But I feel pretty comfortable with the reputation.


      Year: 2006 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      October 04, 2018

      Good Stuff

      I recently replaced the rear wheel bearings in my 98 Mustang GT and had to drain and refill the diff. oil. Royal Purple Max gear oil was my choice. Not having a lift, I had to do this chore on jack stands while lying on my back. I clamped a piece of tubing to the nozzle and put the other end of the tubing into the fill hole. The stuff is thick so, it took a while and when the bottles were 2/3 empty, I poked a hole in the bottom so the rest would drain out quicker. So far, the stuff has been great.


      Year: 1998 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      September 04, 2018


      It definitely oils the gears in your car works like a charm


      Year: 2002 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      June 20, 2018

      The Best Gear Oil

      This is really great gear oil.I think it is the best for your STANG ‘S rear Rick


      Year: 2011 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      June 01, 2018

      only gear oil I use

      I Literally only use this gear oil in all my cars. Gives me a good piece of mind.


      Year: 1999 Submodel: Cobra

      Helpful (4)

    • 5/5

      Installation Time: Less than 1 Hour

      April 15, 2018

      Gear oil

      This is a great product for the rear end upgrade. Bottles are easy to handle and are priced much better than the gear oil at my local part store


      Year: 2001 Submodel: Bullitt

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      March 24, 2018

      2012 Mustang GT.

      Back before I traded my 12 I had changed the rear end cover and changed over to RPMax 75w90. Also changed tranny to Royal Purple. For me was my best choice. Plan to do the same with my 17 GT. No need for friction additive with this .


      Year: 2018 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      January 04, 2018

      Great gear lube

      The shape of the bottle definitely helps with pouring the fluid into the rear end case. I have also noticed how quiet and seems to spin more freely than it did with the factory fluid. Highly recommend


      Year: 2012 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      October 31, 2017

      Works great

      Great product already has the friction modifier in it so it's prefect for rear gears changes only thing is you'll only need two for a 8.8 rear end where the website says it takes three


      Year: 1986 Submodel: Other

      Helpful (6)

    • 5/5

      Installation Time: Less than 1 Hour

      September 19, 2017

      Royal Purple

      This is the oil that came in the installation kit I bought w/ my 4:10 gears. The rear diff sounds quiet, so it must be doing it's job. Royale Purple has a good reputation and has been around for years.


      Year: 2004 Submodel: GT

      Helpful (3)

    • 5/5

      September 15, 2017

      2003 Mach 1

      A must when changing out the rear-end, replaced 3.55 with 4.10 WOW!


      Year: 2003 Submodel: Mach 1

      Helpful (3)

    • 4/5

      Installation Time: Less than 1 Hour

      September 14, 2017

      Differential fluid exchange

      Changed fluid on tear and it works good. Everything seems to be smooth. Works as advertised.


      Year: 2000 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      August 25, 2017


      Its Royal Purple and it already comes with the friction modifier in the oil so you will not need to add or buy it separate.


      Year: 2007 Submodel: GT500

      Helpful (4)

    • 5/5

      Installation Time: Afternoon

      July 01, 2017

      Purple Powerrrr

      The Royal Purple price is great. The product is the best out there. It took me about 1 and half to complete. This is truly the best color out there. Thanx American Muscle for the great products you put out here.


      Year: 1997 Submodel: GT

      Helpful (3)

    • 5/5

      May 30, 2017


      Needed my LSD re shimmed and added new plates since it had to come out. Used the Royal Purple on the recommendation of my mechanic who is a mustang guru. All is good, no problems and the rear runs smooth n quiet. I also added the friction modifier for full protection and maintainence.It's also peace of mind knowing there's good gear oil in the rear for years of worry free driving


      Year: 1994 Submodel: GT

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      May 02, 2017

      Name speaks for itself

      Anyone that knows about Royal Purple knows that its some of the best stuff out there u can get.


      Year: 2017 Submodel: GT350

      Helpful (3)