Gearbox oil

Bro

Paid Member
Hello everyone

I know people have talked about gearbox oil on here a lot in the past but I went to the local parts place a while ago and asked for some gearbox oil and gave them my reg. The oil they said it came up as was EP75W80 and they gave me a bottle that said it was mineral oil

Just wondering if this any good or if I should be using synthetic

Thanks in advance

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Castrol Syntrans 75w90 is what I have in mine

Had redline MTL 75w80 Which I found good but I much prefer the Castrol

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We settled on the Castrol also after trying several others inc' MTL

May I ask, why you prefer Castrol over Redline MTL? I have changed my oil to Motul Motylgear 75w80 and I am not very happy with it (feels notchy and not smooth at all), so wonder which one I will try next. Thanks.
 
May I ask, why you prefer Castrol over Redline MTL? I have changed my oil to Motul Motylgear 75w80 and I am not very happy with it (feels notchy and not smooth at all), so wonder which one I will try next. Thanks.
I’ve personally found that Redline started to feel notchy when pushed, during fast road driving. Admittedly this is on a route with many turns that requires constant shifting.
 
I’ve personally found that Redline started to feel notchy when pushed, during fast road driving. Admittedly this is on a route with many turns that requires constant shifting.
That is exactly what i feel with Motul....it is constant shuffling between 2 and 3 sometimes 4 where I am driving, so quite the same.
Could this be problem with all oils that have 100deg, viscosity around 10 (MTL and my motul, ale original renault fluid too)? Castrol is like 15 i think.
 
May I ask, why you prefer Castrol over Redline MTL? I have changed my oil to Motul Motylgear 75w80 and I am not very happy with it (feels notchy and not smooth at all), so wonder which one I will try next. Thanks.

After a full day of track use the gear change became notchy with the MTL, using Castrol the gear change was more consistant
 
Thank you guys! Very helpful.
I hope this oil will help with longevity of synchros.
It's a shame that even after all those years, noone came with permanent solution, because noone knows the exact reason, why they fail :worried:
Same with the spun rod bearings. (mainly italian and german "autobahn" cars affected, so probably insufficent oil cooling?)
 
Has any body used Fuchs Titan race 75w90 GL5 gear oil? Recently bought the car for track use and on its first outing I had no issues but the gears felt like they were catching teeth (almost) on fast gear changes. Didn't notice this early on so I'm guessing it was when the oil got hot.

The box was rebuilt last year so I'm pretty sure its mechanically sound and this issue only happened when you change gear fast. On the road you can drive it as hard as you like with no issues.
 
Has any body used Fuchs Titan race 75w90 GL5 gear oil? Recently bought the car for track use and on its first outing I had no issues but the gears felt like they were catching teeth (almost) on fast gear changes. Didn't notice this early on so I'm guessing it was when the oil got hot.

The box was rebuilt last year so I'm pretty sure its mechanically sound and this issue only happened when you change gear fast. On the road you can drive it as hard as you like with no issues.
@RSRowe may have tried a 75w90 oil iirc.
 
Hi.

Yep I’ve switched back to 75w80 Sintofluid after having similar issues to yourself…… couldn’t get into gear downshifting quite a few times. No grinding fortunately, so I don’t think the box hasn’t been damaged in the process.
 
75w90 Sintopoid is just the wrong oil to let the synchros/gearbox work properly. It is however the preferred oil for LSD use

Gripper have said to run the oil which is best for your box. The diff itself can put up with any lubricant essentially.

I don’t think heat is a factor in all of this personally.