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trans and OD oil for BN2

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bighealeysource

bighealeysource

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Know that 30 wt non detergent is recommended by many for Healey trans and OD units, and understand about using the non detergent oil versus one with. Any other recommendations ?
Seem to recall one was for one of the Redline products ?
Thanks,
Mike
 
I used straight 40 wt in my Tr-6 with overdrive with good results, However, understanding the reasoning as to why some folks use straight weight, I still use 20/50 detergent same as my motor oil for my Healey with never any shifting or mechanical problems over the years! I know other Healey owners on this forum use 20/50 detergent in there Healeys as well. Thats what the factory recommended in the first place! On colder days, I always drive my Healey about 5 miles to warm the trans oil before engaging the overdrive as to not blow any seals.

I remember talking to John from quantum mechanics about 8 years ago, he said he would not warranty his rebuld of my transmission and overdrive unit for my 73 TR6 if I used anything but 30 or 40 straight weight oil. Mainly because of blowing seals in the overdrive unit if I remember correctly. Also, many people advise against driving in reverse with the overdrive engaged... I just can't remember why? Maybe someone else can chime in on that one!
 
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Thanks Drambuie - going to use 40 wt non detergent. BTW, NAPA carries 40 and 30 wt where most auto parts stores only carry 30 wt.
 
From everything I've read, a straight wt nondetergent oil is the best choice.

Driving in reverse with the overdrive engaged is pretty much fatal for an overdrive. It is, however, impossible to do if the switch on your shifter is working correctly.
 
Just out of curiosity- what difference does "detergent" in the oil make to a gearbox? I know that VW engines run all the bearings if you change from non to detergent oil because it loosens off all the carbon crud and there is no oil filter on a VW but I can't see what difference it would make to a gearbox.

Andy.
 
Thanks for the link Keith. I had read a while back about the 90wt oil overpressure problem and that made sense but hadn't connected with the detergent/non thing.

When I drained the oil after bench testing there was a lot of entrained air bubbles which made the oil look brown and opaque so I guess there is some basis to the discussion. I am using regular motor oil, 20W40 grade I think. The OD shift is extremely fast when cold- so fast it is mildly annoying, but when it is hot the delay is spot on. Just like an enthusiastic change from 3rd to 4th but with no clutch. Pressure is correct when cold.

Andy.
 
One story has it that the detergents in the oil will harm the bronze components, like synchros, in the earlier 'boxes. I have seen the metallic color in a lot of drained oil from old gearboxes. Center shift 'boxes went to different synchros (steel) and the owner's manual reflects the o.k to use multi-grade oil ( assume that means detergents are o.k. ). So I use 30 wt. non-detergent in the early ones and 20w50 Castrol GTX in the center shift ones. I don't think the lack of ZDDP is an issue in gearboxes, like it might be in the engines.
 
From what I have been told detergent motor oils suspend small particles and impurities in the oil, which works well when you are working in a filtered system and they are filtered out, in a tranny without the filter you are better off having the junk in the oil settle to the bottom where it can do no harm. Also I believe the viscosity enhancers can cause frothing or "cavitation" in an overdrive tranny. That being said I have run non detergent 30 or 40 weight as well as 20-50 in Healey and Triumph overdrive tranny's and both have worked fine, don't have any idea if the "suspended particle" theory on detergent oils makes much difference over time, but I suppose if could.
 
In my BN1 I use an Australian product called Penrite Gearbox Oil, straight 40 grade. I went to 40 instead of 30 (which the manual recommends) because of our warm Queensland climate. Is Penrite available in the US? It works very well.
I have also heard that detergent oils are not compatible with bronze synchros, but I thought only BN1s have such parts?
Having recently had the pleasure of driving Andy's 100-6 while visiting New Zealand, I agree your O/D engages promptly, but it wasn't annoying at all!
 
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