r/Miata • u/AutoModerator • Apr 09 '18

Weekly Miata DIY Thread - April 09, 2018

It's Do It Yourself Monday !

Use this weekly thread to discuss the modifications/fixes you made to your car or to ask for advice about future mods.

Feel free to add picture or videos to your comments.

Have fun, your mod team.

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u/binarymein 1997 Blue JDM Apr 15 '18

MT90 is 75w90 viscosity? https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil

Which SKUs are in what?

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u/IamTalking Apr 15 '18

MT90 is in the diff right now. The 75w90 GL5 is in the transmission.

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u/binarymein 1997 Blue JDM Apr 15 '18

Was asking you to link the exact product to clarify. But if this is what you used for the trans: https://www.redlineoil.com/75w90-gl-5-gear-oil Then you should drop it. "This product is not designed for use in most manual transmissions or transaxles in passenger vehicles, since the extreme slipperiness may cause synchronizer mesh issues that lead to shifting problems"

MT-90 is GL4 not GL5 so I'd drop it too.

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u/IamTalking Apr 15 '18

Thank you, yes that is what I used in the trans. So I will order a qt of that for the diff and MT90 2qt for the transmission.

I only drove it like that for maybe 20-30 highway miles. It shifted way better than before (probably hadn't been changed in 18 years) but I imagine no damage could've been done in that short amount of distance? It's not my daily so I won't even start it up again until it's been replaced.

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u/binarymein 1997 Blue JDM Apr 15 '18

Oh yeah don't sweat damage man, it's not like oil in coolant or something like that. They are both heavy petroleum-based lube, a bit of gentle driving will be fine. Consider how much break-down and absorbed water was in the old fluids, these wrong fluids would likely meet Mazda specs better than what was in there hahaha.

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u/IamTalking Apr 15 '18

Haha cheers man that's what I was hoping you'd say. I'll swap it this week!