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Red Line Oils MGB Transmission?

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PAUL161

PAUL161

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I posted this here also as you guys are more into using the best oils in your cars. My wifes 72 B, which has overdrive, has always had a stiff shift ever since the transmission was rebuilt back in 2006. Can I use Red Line MT90 in it and will it be ok in the over drive? I put it in my TF and would like to put it in the B if possible. PJ
 
Paul--

I am sure that someone can give you a more definitive answer but I believe that the viscosity of MT 90/MTL is the same as that of 30 weight engine oil which most folks use in OD transmissions.
 
I consider it more a question of lubricity than viscosity in that box. The synth lube may be a bit too slick and cause the baulk rings to slip rather than grip. I've seen it happen with some additives, too.
 
Thanks guys for your input, very much appreciated. I think I'll just leave the 20/50 in it for now, as the OD works perfectly and that's my biggest concern on the B. Maybe later if someone who is using it in their gear box with OD gives an favorable report. Thanks again. PJ
 
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You may want to pop over to bobistheoilguy.com and see if you can get some info there. It's a website and forum populated by people who are experts in the field. There's also a lot of good info about oils in general.
 
Not having an OD transmission in my Healey I cannot speak to Redline's effect--if any--on anything but the gears but I can tell you that as a result of my having conducted extensive non-scientific testing (meaning driving) the transmission definitely shifts better/faster with less synchro crunch when using the MT90 than with 20/50.

So there....
 
I run the Redline MT90 in both my big Healeys with overdrive. I've had it in my '65 BJ8 street car for about 10+ years now without any issues and I run it in my '57 100-6 MM vintage racer. As Michael stated, it makes a big difference smoothing out gear changing. It also decreases the transmission noise and lowers the operating temperature. All things we desire with our LBC.
 
I should think that Doug's post provides a pretty definitiive answer as to whether or not Redline is good in OD boxes. Interestingly there is a brief but pretty good article in this month's edition of "Vintage Motorsports" on this topic and though there is no specific reference to OD application or suitability the thrust of the article is that 75/90 transmission oil is about the same viscosity as 10/40 engine oil and according to both Royal Purple and Redline engineers entirely suitable for the transmissions in our cars.

If I have any bitch with Redline it is that it seems to seep out of the MG transmissions in my Elvas. I cannot pin the source down--it is almost like the oil perspires on the casings. Perhaps the seals need replacing or perhaps the old AL castings have become porous and maybe I should coat the inside of the castings with that red paint used inside engines?
 
Thanks Doug! You just made up my mind. MT 90 it is. Now I have to figure how much oil the MGB transmission with OD takes. PJ
 
6 pints, got it, thanks. PJ
 
MT90 seems to be fine on the street, but we are not so sure about racing. A friend used it in a brand new OD unit in his TVR (MGB trans) and cooked the OD unit, which they attributed to the oil being too slippery.
 
You know, I haven't received any concrete evidence that Red Line oils won't damage my OD unit in the MGB. Some say it's ok and some say it isn't. So, it's keeping the 20/50 VR-1 in it. I don't want to use my unit as a test platform. The Red Line will be used in rhe TF only. Thanks for all the input! PJ
 
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