Mazda Hypoid SG1 Alternative

[AdmiralYoda]

My 2016 Mazda CX-5 AWD with the 2.5L is due for a rear differential and transfer case fluid change. In the past I've use the OEM Mazda Long Life Hypoid SG1 Gear oil but I'm looking for an alternative. The internet and this forum confirms that the SG1 is a 75W-85 oil.

Without much evidence, this forum seems to recommend the alternative to Mazda SG1 is a GL-4, 75W-90 oil because "The hypoid gear metals are softer". I 100% agree in a manual transmission but I don't see how this applies to Mazda's transfer case.

A quick internet search says that the main difference between GL-4 and GL-5 is that GL-5 has more pressure additives and that GL-4 has less sulphur which can be corrosive to brass synchros. GL-5 is generally preferred for Hypoid gear sets as it handles more extreme pressures.

Below is a exploded diagram of the Mazda KN01-27-500A transfer case. It looks like a simple hypoid gear set to me. The input shaft is attached to the automatic transmission which does the engagement/disengagement of the AWD.

Also below is an exploded view of the rear differential. I can't see a single reason why a GL-5 oil would NOT be okay. Anyone have any thoughts?

 

[zfasts03]

didn't realize they both use the same fluid for the Transfer case and the rear diff.

Down the road I will be changing mine also.

 

[RedSpider]

Without much evidence, this forum seems to recommend the alternative to Mazda SG1 is a GL-4, 75W-90 oil because "The hypoid gear metals are softer".

Do we (or anyone else) know if Mazda SG1 is actually a GL-4 fluid? I've seen thread after thread after thread about this wonderjuice but have never seen anything definitive as to whether or not its a GL-4 or GL-5.

 

[AdmiralYoda]

@RedSpider My thoughts exactly. The rear differential and transfer case look like your plain old ring and pinion setups, no synchros at all. I can't imagine any soft metal wear items in these gear setups.

I'm just going to put synthetic GL-5 in there.

 

[danbfree]

Do we (or anyone else) know if Mazda SG1 is actually a GL-4 fluid? I've seen thread after thread after thread about this wonderjuice but have never seen anything definitive as to whether or not its a GL-4 or GL-5.

@RedSpider My thoughts exactly. The rear differential and transfer case look like your plain old ring and pinion setups, no synchros at all. I can't imagine any soft metal wear items in these gear setups.

I'm just going to put synthetic GL-5 in there.

It says GL-4 long life hypoid gear oil right on the bottle of SG1, which is weird as GL-5 is typically used for hypoid gears, but regardless... so I used Royal Purple Max Gear 75w-90 in my '22 Mazda 3 AWD Turbo, that also uses SG1, in both the transfer case and rear diff. It is what is called a GL4+, it is safe for use with softer metals when GL-4 is called for but also meets GL-5 requirements. The RP claims exactly this, and has the additives for hypoid gears already, so it will be safe for use/warranty. https://royalpurpledirect.com/max-gear-75w-90-synthetic-gear-oil/

 

[RedSpider]

You're right it does show as GL-4, I dont know what bottles I was looking at before but the pictures I googled didnt show it. But I googled some more just now and yes the ones I just looked at do say GL-4.

 

[danbfree]

You're right it does show as GL-4, I dont know what bottles I was looking at before but the pictures I googled didnt show it. But I googled some more just now and yes the ones I just looked at do say GL-4.

Exactly, but don't worry about it, even if you use fluid that is GL-4 safe and has the hypoid gear additive already, people will still gaslight you for thinking using 75w-90 instead of 75w-85 won't void your warranty, LOL...

 

[randomhero439]

It really comes down to the roll vs slide ratio with gearing. Too much sliding and you need a GL5. Just worked through this when working with an oil manufacturer for a transaxle im designing. Next those gear sets might also be spiral bevels, not hypoids like the oil suggests. Different tooth geometry, and zero offset for better NVH and efficiency, but not as good for tooth strength. Last, there are no “soft metal” hypoid gear sets. It’s all case carburized gear steel. Transmissions, axles, ect usually use the same steel unless their is something fancy going on or their is a band aid and a premium steel is needed to fix it.

 

[danbfree]

It really comes down to the roll vs slide ratio with gearing. Too much sliding and you need a GL5. Just worked through this when working with an oil manufacturer for a transaxle im designing. Next those gear sets might also be spiral bevels, not hypoids like the oil suggests. Different tooth geometry, and zero offset for better NVH and efficiency, but not as good for tooth strength. Last, there are no “soft metal” hypoid gear sets. It’s all case carburized gear steel. Transmissions, axles, ect usually use the same steel unless their is something fancy going on or their is a band aid and a premium steel is needed to fix it.

Well said. It is unusual that the OEM fluid is a GL4 Hypoid gear oil, but it is... So in that case I'm glad I used something that met both of those requirements, which again I agree is really strange as hypoid gears pretty much always need GL5. The Royal Purple is GL4/GL5 and Hypoid gear ready like the OEM stuff (GL4 hypoid oil) and a super close weight (75w-90 vs 75w-85 SG1), so I know I'm covered as far as warranty and protection.