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Redline MTL or equivalent?

SteveHall64Healey

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My BJ8 has had ‘notchy’ shifting and the synchro on second gear has been iffy. I use 20w50 with ZDDP and change it every season. Someone recommended Redline MTL as an additive that helped with the same problem in their (non-Healey) car. Has anyone used this or equivalent and what results were obtained?

thanks
steve
 

Gliderman8

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I use straight Redline MT-90 gear oil in my transmission and I’ve never regretted it. It shifts smoothly with no sticking at all. I’m not sure about an “additive”.
 
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I second Elliot's recommendation; I've used MT-90 for many years with nary an issue (except maybe a bit more leaking, although my last rebuild with careful attention to gaskets/sealant and the square cross-section O-rings seems to have stopped most of it). You don't want/need ZDDP in the gearbox/OD, it mainly helps preserve cam lobes and lifter faces; too much can actually be detrimental.
 

Gliderman8

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Just to be clear, you’re recommending Redline MT90 75w85 GL4 gear oil?
That's what I used in my Toyota 5-speed transmission. I'm quite satisfied with it. I am recommending that you speak with other Healey owners to get additional feedback and then make your own decision. As for me, I think it is performing well.
 

twas_brillig

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I used Redline in the transmissions and differentials of our 'classic' cars. My notes are that the stock Healey o/d transmission would use MT-90-GL4 (same as we currently put in the Toyota 5 speed); the differential 75W90 GL-5 Gear Oil.
Have a look-see at the Redline web page; phone them if you can't find what you're looking for as they've been very helpful when I've called. Doug
 

dougie

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My BJ8 has had ‘notchy’ shifting and the synchro on second gear has been iffy. I use 20w50 with ZDDP and change it every season. Someone recommended Redline MTL as an additive that helped with the same problem in their (non-Healey) car. Has anyone used this or equivalent and what results were obtained?

thanks
steve

I've used Redline MTL oil in my '65 BJ8 trans/overdrive for the last 20 years and have been happy with the results. Only downside is the synthetic oils will leak a little more through the seals than general 30 wt.
 

RAC68

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Hi All,

For the first 30 years of its life, I used the standard specified 30W non-detergent oil recommended in the manual. After that, I went with the recommendation of others and switched to Redline MTL. Although I saw little difference in trans or OD shifting, I did find Redline seemed to be able to escape from places I had never experienced. As a result, I mixed the Redline with 30W ND oil and have been happy with the trans/OD performance with little or no leakage.

Redline MTL works good but, as Dougie stated, expect leaks from everywhere.

Ray(64BJ8P1)
 

Jack T

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If you read the label on MT90, it says that it is a substitute for up to 40w motor oil in gearboxes. In a freshly rebuilt 'box I changed from 30w mineral oil to MT90 and the difference was remarkable. And the od works perfectly.
 

Gliderman8

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Hi All,

For the first 30 years of its life, I used the standard specified 30W non-detergent oil recommended in the manual. After that, I went with the recommendation of others and switched to Redline MTL. Although I saw little difference in trans or OD shifting, I did find Redline seemed to be able to escape from places I had never experienced. As a result, I mixed the Redline with 30W ND oil and have been happy with the trans/OD performance with little or no leakage.

Redline MTL works good but, as Dougie stated, expect leaks from everywhere.

Ray(64BJ8P1)
I've never had any leaks what-so-ever but then again, I have the Toyota W58 transmission so maybe tolerances are tighter. It is a good product.
 

vette

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I would not use 20/50w motor oil in the Healey Trans & Over drive. The original shop manual for the Healey says to use 30w motor oil. I put nothing thicker than that in my Healey Trans w/od and have had no problem for over 20 years.
 
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IIRC--I don't have it handy, I'll check later--that later versions of the shop manual like Bentley's endorse 20W-50 in the gearbox/OD. Really, any good lubricant oil will work, but you should probably avoid extreme pressure ('EP') gear oils like GL-5 that contain sulfur-based additives that can (supposedly) react with brass and bronze. MT-90 is a GL-4 which has less EP additives, but I rebuilt my BJ8's gearbox/OD a couple years ago--I've used MT-90 for decades and many miles--and the only wear was the ends of the lay shaft, a known wear spot and (even the synchros showed little wear, but I replaced them on principle). I replaced the lay shaft with a DW 'uprated' shaft, and even the worn shaft wasn't causing any issues at about 120K miles. I discussed this issue with David Nock, owner of BCS, because I was concerned about the bronze thrust washers in the differential; he said the only thing he'd ever seen was some blackening of the thrust washers, but no significant wear. Still, I would not use a GL-5 in a Healey gearbox/OD; I'm using Redline 75W-140 GL-5 in my differential, which helps a little to quiet a whine (I seen now Redline has a 80W-250 GL-5!).

Edit: Found some info I hadn't seen before:

https://www.amsoil.com/newsstand/auto-and-light-truck/articles/dont-forget-the-gear-oil/

https://www.farmoyl.com/resources/sae-viscosity-grades

https://www.thelubricantstore.com/understanding-the-viscosity-grade-chart
 

vette

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I don’t know of any original Healey transmission that 20/50w oil was specified for. But some other little british cars did specify it, as an example MGBs.
 

vette

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My Bentley manual for the 100/6 & 3000 specifies 30w oil for the transmission.
 
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I don’t know of any original Healey transmission that 20/50w oil was specified for. But some other little british cars did specify it, as an example MGBs.

Good down to 10degF ('Engine and Gearbox'):

OilChartR.JPG

From:

BentleyCoverR.JPG
 

vette

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I stand corrected Bob. Can't dispute the written word. For years I have been using the Driver's Handbook to reference quick facts. It does not specify 20/50 but only shows viscosities up to 20/30w. It is curious that where 20/50 is specified in the Bentley manual that only certain manufacturers do so.
Here is the page from the Driver's Handbook:
 

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vette

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tried to make that page bigger:
 

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My hunch is multi-vis oils were just becoming widely used in the 60s and 70s; as more multi-vis brands became available they were arbitrarily added to the 'recommendations.' I doubt much if any suitability/compatibility testing was done and, who knows, there may have been some 'backroom,' er, discussions between the auto manufacturers and the oil companies about what brands should be recommended. Some current owners use a 20(?)W-60 multi-vis; I'm comfortable using Valvoline 20W-50 (my engine builder OK'd it).

Edit: The high-strung, DOHC Coyote 5.0 in my Mustang takes 5W-20 (something about getting pressure to the timing chain tensioners ASAP on startup). Go figure.
 
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