[Healeys] Trans oil foaming

Roger Grace roggrace at telus.net
Wed Mar 8 09:16:55 MST 2017

Now heard back from Castrol/BP.
Their response is that they do not recommend the use of their non-detergent 30 oil in manual transmissions.

Castrol does not recommend our Non-Detergent 30 oil for manual transmission applications, and we believe the foaming was likely caused by some type of contamination, perhaps water in the transmission. 
Unfortunately Castrol does not offer a manual transmission fluid product in Canada or the US.

This phenomenon is still a mystery to me as there certainly was no water in the transmission as had drained it 2x before noticing the foaming.


From: Olin Brimberry 
Sent: Friday, February 24, 2017 12:13 PM
To: Roger Grace 
Cc: Healey List 
Subject: Re: [Healeys] Trans oil foaming


Your post is good timing for me. I just recently replaced my gearbox and installed Shell ND 30wt. After having a reoccurring drip, I thought it would be wise to check the oil this past weekend. I forgot to check the level before I cranked the engine, so I shut it down after it had run for about a minute.  Much to my surprise, I noticed a lot of oil foaming on the dipstick. The oil level was just fine, midway between high and low.  Always heard oil foaming was a problem to maintaining proper lubrication of the parts. In engines, I understand that foaming can be caused by over filling the crankcase.  Hopefully, the level is high enough that the foam is above the rotating gears and bearings. 

So, I too would be curious what the experts say.  I too have the MT90 at hand, but was concerned that the drip would possibly be worse if I switched. 

Olin K. Brimberry, PE 
HunterBane Engineering, PLLC
919-803-4274 (office)
919-522-1608 (mobile)

On Feb 24, 2017, at 11:18 AM, Roger Grace <roggrace at telus.net> wrote:

  I recently had the OD on my BJ8 apart to replace some parts – bearing/accumulator/gaskets/O rings etc.
  For a first sort of sacrificial oil fill I decided to use a non detergent Castrol 30 wt oil. Date codes less than 18 months old. Plan was to switch to the expensive Redline MT90 after testing and after a few hundred miles. This 30 WT oil is often recommended by OD experts. I have built an electric variable speed rest rid to be able to test the transmission outside the car.
  Overdrive worked fine and transmission sounded OK and ran it for about 2 hours to get the temp up (52C on OD case) and hunt for leaks.
  So far so good.

  Then after a few days of standing, and 2 minutes of running, I drained the oil (to fix a leak) and was amazed to see that the oil had foamed badly and there were big classic fish eye bubbles on the surface of the oil. Ambient was about 14C. I did note that the oil coming out of the transmission was somewhat foamier than that from the overdrive drain plug.
  See enclosed pix.
  After standing overnight the oil looked normal again.

  What disturbs me is that unless I had drained the oil I would not have been aware of the foaming and put it into service .... 
  Have now replaced with the MT90 that shows no sign of foaming on the dip stick.
  Wonder if others have any ideas about this weird phenomenon and is it  a concern ?

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