[Healeys] Tranny and OD drain plugs

[Dave & M]

Hi Guys,

 From Redline's own specs:

The full description of MTL is "SAE 70W80 API GL-4 Gear Oil. Satisfies
the gear oil viscosity requirements of 70W, 75W, & 80 AND motor oil
viscosities SAE 30, 10W-30, & 5W30."

The full description of MT-90 is "SAE 75W90 API GL-4 Gear Oil.
Satisfies the gear oil viscosity requirements of 75W, 80W, & 90 AND
motor oil viscosities SAE 40, 10W-40, & 15W40."

They are both higher friction coefficient oils which helps
synchronizer & overdrive clutches work better & do not contain large
amounts of sulfur compounds which tend to damage bronze components in
the older transmissions. MTL is no more "slippery" than MT-90.

MTL is equivalent to 10W30, MT-90 is equivalent to 10W40. If you are
using the car in hot climates, the slightly thicker MT-90 tends to
work better. In cold climates,  the MTL might be better.

In my personal experience, either RL oil gives better shifting & OD
operation than the original recommended 30 weight engine oil, & also
better than the sometimes used SAE 20W-50 engine oil.  Multi grade &
synthetic oils were not available when the original car manuals were
written. There are endless arguments & opinions about which oil to
use, make your own decisions.

Regards,
Dave Russell

Ronald J. Ray wrote:
 > John,
 >
 > Your email seems to contradict one from David Nock some weeks back
 > when he said:
 >
 > "The gearbox and overdrive call for 30 wt oil. The MTL is a 75W/80
 > wt GL4 gear oil that has a SAE viscosity of 10/ 30 wt engine oils.
 >
 > The MT 90 is a 75W90 wt GL4 gear oil and the viscosity is that of a
 >  90wt gear oil which is to heavy for the Healey gearbox."
 >
 >
 >
 >
 > Ron Ray
 >
 >
 > -----Original Message----- From:
 > ronald-ray=sbcglobal.net at autox.team.net
 > [mailto:healeys-bounces+ronald-ray=sbcglobal.net at autox.team.net]On
 > Behalf Of John Mitchell Sent: Sunday, August 05, 2007 6:22 AM To:
 > TERRY COLL Cc: healeys at autox.team.net Subject: Re: [Healeys] Tranny
 >  and OD drain plugs
 >
 >
 > MT90 if formulated to be compatible with older transmissions that
 > contain bronze metal parts. Also MTL supposedly is too slippery for
 >  use in overdrive units and can cause slippage.  John Mitchell