[Healeys] Russ Thompson

Randy Hicks healey100m at me.com
Wed Aug 9 07:15:22 MDT 2017

I have used Redline MT-90 in both 100M's and BJ8 transmissions for 8 - 10 years now exclusively.

6 trips across the USA and Canada, 80,000+ miles. Another one in September.

No issues at all. Nice smooth shifting. MTL is thinner and tends to leak more out of the 100’s tranny.

Highly recommend. 


Randy Hicks
'56 100 M  White/Black
'56 100 M  Florida Green/OEW
'65 BJ8
'53 MGTD
'77 450 SL
Healey100M at me.com

> On Aug 9, 2017, at 7:44 AM, Charlie Baldwin <mgcharlie at comcast.net> wrote:
> Mike,
> You have probably stepped in it by getting an oil discussion started again.  
> But to answer your question without adding my opinion to it, I believe that when someone on the list contacted Red Line, they recommended MT-90, which from memory is 40 wt.  Check Red Line's website:  https://www.redlineoil.com/Products.aspx?pcid=7 <https://www.redlineoil.com/Products.aspx?pcid=7>
> They make a good argument for using a gear rated oil in a transmission as Harold also outlines below.  As he mentions and we have discussed previously, it seems that the synthetic transmission oils do leak a bit more.
> Charlie
> On 8/8/2017 11:24 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 <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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