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Hello, on Monday I have an appointment at the mechanic to change all the fluids in my car because it already has 40,000 miles and I only periodically change the engine oil.
the mechanic has budgeted these for me.
Brake fluid: Motul dot 5.1
Manual transmission fluid: Motul Gear 300 75w90
Rear differential fluid: Motul gear competition 75w140
Antifreeze: Motul Inugel Optimal

It is all Motul because my mechanic works only with that brand. In Spain it is difficult to find American brands such as Royal Purple

The use of my mustang is a daily use. Is it a good choice?
 

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I use the 5.1 brake fluid. Make sure you change it every 2 years for normal driving. More often for track use. It is good stuff. Not familiar with the differential fluid. Make sure it has the friction modifier.
 

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I think Motul is generally real good stuff, so generally should be a pretty good choice. I think the manual transmission is picky about its fluid so you might want to check the threads on here for the latest recommendation. DOT 5.1 brake fluid isn't really needed unless you are road racing the car, DOT 3/4 should be fine.
 

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Yes fluids are one of those option deals. Everybody swears by a certain one. I will second JBert though to say these transmissions are very finicky at best and the wrong fluid can cause issues like gear whine, lockouts, or grinding... I know this form unforunate experience.
 

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After looking at his profile showcase info I finally found out what we are going to use these fluids in is a 2014 GT Premium. I always want to verify what the owner has in case they posted in the wrong forum.


Yes, all those fluids are good to use in your car.

Don't worry about the 5.1 fluid. Just be sure you do not use Dot 5.

Dot 5.1 is probably more than you need but I think using expensive engine oils for daily driving is overkill too if the oil is changed at recommended intervals.
 

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I use the 5.1 here in the desert. Mountain driving with temps above 110 will give a little better edge. Long down hills with blind curves at 75mph(which almost no one obeys) can come to a dead stop. I agree for normal driving one would not need it.
 

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DOT 3 is what 3-4 years while DOT 4 is every 2-3 years, and DOT 5 and DOT 5.1 is evert 1-2 years, right? These are all under relatively normal driving conditions. Under heavy braking, high temps, or humid should be changed more frequent. Am I remembering all this right?
 

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DOT 3 is what 3-4 years while DOT 4 is every 2-3 years, and DOT 5 and DOT 5.1 is evert 1-2 years, right? These are all under relatively normal driving conditions. Under heavy braking, high temps, or humid should be changed more frequent. Am I remembering all this right?
Just go with 1 schedule for daily-drivers that use any of the three non silicone brake fluids (3,4,& 5.1), otherwise it gets too confusing. If you track, or slam the brakes a lot on the street then use a shorter schedule.

Dot 5 is silicone based and has its own rules. I'm not aware of any Mustang that comes from the factory with it. In fact none of the high performance competitors come with it either.
 
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