[Healeys] Russ Thompson

Bob Spidell bspidell at comcast.net
Wed Aug 9 09:06:43 MDT 2017

Ah, one of our favorite 'religious topics.'

FWIW, I've used MT-90 for many years and probably at least 60,000 miles 
and swear by it (I ought to keep track of this, but record-keeping is 
not my strong suit).  I never bought the 'use non-detergent oil so the 
sludge can build up in the bottom of the case' theory (anybody want 
'sludge' in their arteries?).  Unless you constantly grind gears there 
shouldn't be a lot of loose metal in a gearbox/OD (IMO).  When I do 
change out the Redline the only metal particles in the oil are extremely 
finely ground particles--you can't feel them if you rub the oil between 
your fingers--of what appears to be brass (you can only see the 
particles in bright sunlight).  I presume the brass is from the shifting 
forks wearing down; I expect using synthetic oil mitigates--but can't 
eliminate--that.  My OD screen with magnets never has anything 
appreciable on it, and when I had the gearbox out the bottom and side 
walls were spotless.  A lot of greases--e.g. molybdenum and lithium--are 
finely ground soft metals suspended in oil, and brass is a soft metal.

I used 20W-50 dino oil for a few years/thousand miles but tried the 
Redline hoping to get a little quicker engagement from a hot OD.  I 
wasn't expecting it, so no confirmation bias, but I swear the gearbox 
shifts smoother*.  Yeah, it's harder to contain but that's a small price 
to pay IMO.  I've gone through the gearbox once already, and will be 
doing so again soon, and the gears appear perfect so either type of oil 
is good as far as lubricating properties.  My OD has almost 200K miles 
on it and while I have it out I'll probably check the accumulator rings 
and bore, and the pump, and as I already have a new one I might change 
the solenoid, but on the advice of this list I'll otherwise leave it 
alone.  I use MT-90 in my BJ8 and BN2, and Redline gear oil in both 
(75W-90 in the BN2, and 75W-110 in the BJ8, which quiets a mild whine a 
bit).  I'm contemplating going to a synthetic oil in the BJ8 engine 
eventually as the PCV has all but eliminated the leak from the rear 'seal.'

Like our cars, most of us were 'manufactured' in the 50s and 60s; if you 
follow the 'use what the factory recommended in 1959' trope we should 
only allow doctors to treat us with medicines and surgical techniques 
available then (no arthroscopic surgery for you).  Lubricants have come 
a long way in the last 60 years (one possible exception is the 
reduction/elimination of ZDDP in engine oil, but we have plenty of 
alternatives and I think we all appreciate cleaner air).


* When I bought my Mustang GT, I thought the shifting action was rough 
and 'notchy.'  I checked the Mustang forums, and got a recommendation to 
use synthetic gearbox oil, specifically Royal Purple Synchromax (the oil 
recommended by Ford is actually an ATF). Sure enough, the shifting 
action improved and, supposedly, the RP 'conditions' the gearbox over 
time so it keeps improving.  I can't prove that, but I don't dispute it 

On 8/8/2017 8:24 PM, Harold Manifold wrote:
> Mike,
> I am new to the Healey world but I am an engineer with an automotive 
> background who recently had a BN4 transmission with an overdrive 
> completely rebuilt. I could not find a consistent answer on the 
> recommended oil for the transmission. The original Healey manuals are 
> not consistent either, the shop manual recommends 20W50 and the Healey 
> service bulletins from the day recommend 30W. Coming up with the right 
> oil is further complicated by the design of a Healey transmission 
> which is two different transmissions with a common oil system. One 
> transmission is a traditional gear type with syncro rings that are not 
> compatible with the additives in modern gear lubricants and the other 
> is a hydraulic pump. I am sure there will be much disagreement but 
> these are the steps I went through to select the oil I would use:
> 1. The additives had to be compatible with brass and other soft metals 
> used in older transmissions.
> 2. The oil should be designed to work with gears and have some level 
> of EP protection. Note very few engine oils meet gear oil specifications.
> 3. The oil should have a viscosity similar 30W engine oil which was 
> recommended in an Austin Service bulletin in 1960 replacing 20W50.
> The oil that best fits all of these requirements is a 70W-90 GL4 gear 
> oil. Red Line MT-90 meets this specification as does Pennzoil 
> Synthetic 70W-90 GL4. I picked the Pennzoil as it costs less than the 
> Red Line but both should work well. Do not use a GL5 as the additives 
> are not compatible with brass. I looked into why Austin switched their 
> recommended oil from 20W50 to 30W and concluded it was for a lower 
> viscosity at lower temperatures i.e. when the transmission is cold. 
> Viscosity is another important consideration. 70W-90 GL4 has the same 
> viscosity as 30W engine oil above 35 degrees C and a better low 
> temperature viscosity. The only downside I have seen with Pennzoil 
> Synthetic 70W-90 GL4 is that it can get through even the smallest 
> openings and cracks and the transmission may leak a little more but 
> that is evidence the oil is getting every where it should. I have 
> heard Red Line MT-90 doesn't leak as much as the Pennzoil.
> For those that may doubt the viscosity claims please note that engine 
> oils and gears oils are classified differently and should be compared 
> by looking at the numbers on the can. See the attached viscosity curve.
> I trust this helps but I want to emphasize this is the oil I use and I 
> recommend you reach your own conclusion.
> Harold
> ------------------------------------------------------------------------
> *From:* Healeys [mailto:healeys-bounces at autox.team.net] *On Behalf Of 
> *Michael MacLean
> *Sent:* Tuesday, August 08, 2017 5:47 PM
> *To:* Healey List
> *Subject:* [Healeys] Russ Thompson
> Through a reference from the list I am having Russ Thompson in 
> Northridge, California rebuild my BN2 transmission.  It is a low 
> mileage (10,000 mi. approx) transmission, but I wanted to be able to 
> put it in and not have to take it back out again. Good thing I took 
> this precaution.  Russ found the overdrive stuck and would never have 
> worked.  Today he showed me the accumulator piston.  The smaller 
> center piston was scored from dirt or crap in the oil.  Russ replaced 
> it with a one piece piston from a Triumph overdrive.  There was a huge 
> spring below it.  Anyone heard of this?  He said engagement will be 
> real positive now.  Even with the low mileage, the number 2 synchro 
> was toast and will be replaced.  The other two were fine and will be 
> re-used.  All the gears showed very little sign of wear.  The reverse 
> gear had some surface rust on the teeth, but that can be blasted and 
> it will be fine.  Getting closer to having the drive train is the car.
> I know I am going to start a discussion, but Russ recommends using 
> 40wt motor oil for the transmission.  Anyone know what weight Redline 
> MTL is?
> Mike MacLean

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