Redline 75W90 in manual trans. Should I swap?

[rjd2]

Hi all-I am restoring a DMC-12 that hasn't been on the road in 30 years. We JUST got the car running, and have not gotten it on the road yet. When I was doing all the heavy lifting aspects of the restoration, I changed the gear oil to Redline 75w90 (standard, non NS). Should I dump this for something better? What is the best transaxle fluid to use these days? I have searched the forum history, and saw mention of Lucas 80w90. This better? Thanks for any tips!

https://www.amazon.com/Lucas-Oil-LUC...0&sr=1-28&th=1

[82DMC12]

Redline seems to have mixed results. I've seen people I trust A LOT on DeLorean forums saying they felt the transmission didn't feel as smooth with Redline. I would get rid of it and put in regular old Valvoline 80W90 from NAPA (and sometimes even Walmart!)

[David T]

Any good, branded 85-90W gear oil that is not GL-5 should be fine. In Lotus's they use MT-90 but those boxes are under a lot more stress. It is more important that you have enough gear oil than the actual type (at least in Deloreans).

[rjd2]

Any good, branded 85-90W gear oil that is not GL-5 should be fine. In Lotus's they use MT-90 but those boxes are under a lot more stress. It is more important that you have enough gear oil than the actual type (at least in Deloreans).

so does that mean I want a GL4 type oil? This is getting very confusing for me. It looks like GL5 is intended for hypoid gears. Most of the 85W90 gear oil I am finding is designated as "hypoid gear oil".

[82DMC12]

Personally I've been using this for 23 years and it seems to be working well. I just had my manual transmission apart and everything looked like brand new inside.

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[David T]

The Delorean transmission (a Renault UN-1) is unusual in that the same oil is used in the transmission AND the final drive. GL-5 is not supposed to be used where there is bronze, the syncros in the transmission are made of bronze.

[82DMC12]

There is another thread on here where things seemed to kind of end up that Castrol Axle Limited Slip 80W90 was a good oil to use, but also some had good luck with Redline 75W90NS GL5 which does say all the right stuff concerning synchros.

Never used either of them myself. As I said, I've been using that Valvoline stuff for a long time and never one had gear synchro issues, clashing, etc that were not related to clutch problems. I had the transmission open this winter and everything looked fine inside including the synchros but I didn't have a brand new set to compare to. This transmission has 69,000 miles on it.

PXL_20220907_203533102.jpg

[Helirich]

I think it will be fine. Personally, I would switch to synthetic oil. Since you have new oil in it, I would drive it ten miles or so and then drain it while it?s hot. This will keep any junk in it suspended and should drain with it. I recommend full synthetic Ams-oil. Do not put Royal Purple in it. I have some issues with RP although they probably won?t hurt in this application.