Hi everyone,

Recently I bought a CX5 2017 with a mileage of 100491 miles. So far it’s been pretty solid and previous owner has maintained it well. I bought it from a dealership and they don’t have much of history record about the vehicle even though I have access to some of the records through CARFAX. I have seen a couple of posts about rear differential failure and replacement. And when I check the manual there is no such mention about the differential fluid change. Do I need to check and change it or am I good with how it is right now.

Thanks.

 

AWD or FWD?
While there is no "recommended" mileage from Mazda most differential lube change is suggested at 30,000 to 50,000 miles.
But it also depends on what you do (towing) and where your use (off-road) your CX-5.
If you decide to change it and you have an AWD, then change the transfer case oil and the same time.

 

It is an AWD. Since I don’t have any records about the fluid change, I was thinking of doing it. So I have to change the differential fluid and the transfer case fluid at the same time ?. Can I know what type of fluid and an estimated cost for both ?

Thanks for the info.

 

You use the same for both cases, Mazda Long Life Hypoid Gear Oil SG1.
It runs about $30 a quart and you need 0.48 quarts for each case or 15.36 ounces.
Which means you only need buy a quart.
There are substitutes but it is up to you to make that decision.
No, you don't have to change them at the same time, but many people do as it's the same fluid and you'll know both were done at the same time(mileage).
For what it is worth, Mazda doesn't recommend changing the differential oil unless it's been under water (hence the off-road in my originally reply).
Per manual.

1. If this component has been submerged in water, the oil should be replaced.
   

 

This is very helpful. It’s my first Mazda and I don’t have a good idea about the maintenance in these. Just to make things clear, if the vehicle doesn’t do any type of towing and no off roading, should I keep the fluid unchanged ? Or as scheduled maintenance is it always good to change the fluid at every 30000-50000 miles ?. As you mentioned before, in the manual it only states to replace the fluid if the component has been submerged in water.

Thanks.

 

Welcome to forum

It seems that you are an eager DIY and it's your new (used) vehicle.
Unless you are on a budget if you are like me then I like a base line set for the fluids.
It is a well worth investment in the time and money.

 

As Cali said, fluid change is always a good thing, especially when you don't know when it was last done, or if it was ever done.
Don't forget you'll likely need to replace the seals on both as well.

 

Thank you for all the information and suggestions. Yeah, since I don't have any idea about whether it was done before or not I'll do it asap.

 

 

I recently purchased 2020 CX-5 @ 82K kms and have begun replacing fluids for baseline. It's my first AWD so I now have front transfer case and rear diff. Of course the manual states change only if cases get submerged implying lifetime fluid. From experience, many fluids like CVT are also rated lifetime which, I've chosen to ignore. Common sense and chemical physics suggests any fluid when constantly exposed to hot/cold/hot/cold will degrade. Indeed, some so called lifetime fluids I've replaced are often blackened from burning meaning degraded effectiveness to lubricate and protect gears.

So, I too will change the front transfer and rear diff fluids regularly as preventative maintenance. I'm scheduling around the 96K-100K km mileage mark. It's an easy and "fun" job. I'll be using Redline's 75W85 hypoid fluid which is equivalent to Mazda's SG1 fluid. It's the same OEM fluid I use in a Toyota Tundra with great success so, kept in stock in my garage.