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Synthetic Fluids

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Dave Richards

Dave Richards

Jedi Knight
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I’m considering changing motor, transmission and differential to synthetic fluids. From what I’ve read, “Red Line” seems high on everyone’s list. Is there a consensus on this?

I’ve read the transmission, especially the synchronizers operate considerably better with synthetic oil. Has this been anyone’s experience?

I’ve selected 20-50 for the motor and MT-90 for the transmission but, I’m not sure what to use in the differential, and not even sure it’s necessary in the diff.

Thanks, Dave /ubbthreads/images/graemlins/driving.gif
 
This was discussed in the past:

https://www.britishcarforum.com/ubbthread...true#Post128178

is one.

The Forum has a "search" capability and if you use the terms MT90 or Redline you should be able to dig out past messages about them.

Redline also do a gear oil 75W90 for diffeentials that would probably be suitable. I've some for mine, but I've not yet got to the point where I need to put it in....
 
I think that many modern oils are blends of dino & synthetic.

MTL & MT90 are synthetic gear oils which are rated GL4 & lower. They don't have as much sulfur in them as GL5 rated oils. Sulfur is thought to degrade the bronze synchronizer rings which are found in many "old" gearboxes. Also, MTL & MT90 are less slippery which helps the synchronizers work more effectively.

With GL5 rated oil, sulfur is used as an extreme pressure additive. Hypoid type gears such as rear axles are subjected to extreme sliding pressures which the sulfur is intended to deal with.

Motor oils range from petroleum (dino) based, to fully synthetic, to blends of the two. I doubt that it matters much which motor oil you use. Anything in the 20-50 viscosity rating is usually good. If you decide to go with a fully synthetic motor oil, do not rely on the claimed extended change intervals. Some synthetic motor oils tend to leak out of some engines more easily.

My suggestions, there are dozens of choices & opinions:
Gear box, Red Line MT90
Rear axle - a good GL5 rated gear oil SAE 80W-90.
Engine - any of the good SAE 20W-50 commonly available oils.
D
 
Thanks, I should have done a search, the post was very helpful.
 
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