Redline MTL or equivalent?

[DerekJ]

Multi grade oils did not exist when Austin Healeys were first produced so a single grade needed to be specified. 30 weight was probably a reasonable compromise as the engine had to be able to turn over in winter and flow oil as quickly as possible, so a single grade 40 or 50 would have been too heavy. I’m currently running Mobil 1 10w 60 Motorsport oil.

 

[vette]

Good Morning All,
I am using the Valvoline VR1 20/50 in my engine but not in the tranny. I am using straight 30w in the tranny & OD and have been driving with that for over 40k miles now. May Healey just turned over 100,000 miles, it had about 60k on it when I bought it 20 years ago. Its working super to this day.
I tend to go along with Dereks idea that multi grade oils weren’t every common when the Healey was at its zenith. I was VERY surprised to see that the Bentley Manual recommended 20/50 for the trans/od. Considering that the specs have always said the same lubricant in the engine is what to use in trans I can see how that specification for got written into it. I personally think 50w is too thick especially for the od and I think 20w it too light for the trans. i can see how new formulation such as Red Line can work with lighter viscosities because of there modern formulations but in leu of that I stick with original specs.

 

[HealeyRick]

More food for thought. The owners manuals specified 30W Non-Detergent motor oil. The reason given was since there is no filter in the transmission, a non-detergent would allow wear particles to sink to the bottom as opposed to a detergent keeping them in suspension to be ground up some more. Doesn't sound like too many are using non-detergent now.

 

[John Turney]

Newer engines have closer tolerances and requirements to meet mileage standards, thus the move to lower viscosity oils.

 

[John Turney]

I had the larger accumulator installed in my OD when it was rebuilt. With SAE 30 in the trans, the OD would shift rather harshly. I now have 20W/50 and, while quicker than original, it is more gentile and leaks less.

 

[RAC68]

Hi All,
In a mult-viscosity oil as John is using, I would expect the cold weather viscosity to bottom out at 20W with higher viscosity as the weather and transmission raised in temperature. Does anyone know with the average or normal trans/OD fluid operating temperature profile would be?

Since a synthetic oil is engineered to provide a much more stable viscosity profile, what viscosity would appear to provide the best fluid operation within the trans/OD during normal operating performance?

Over the years I have never found answers to these questions and many owners have experimented with from ATF to Gear Oil. There determination of success was usually based on operation impression with little technical specification to back it up. How can we derive a better evaluation of how different fluids perform in these units?

Just my thoughts,
Ray(64BJ8P1)

 

[Bob_Spidell]

I'm not a tribologist, but I've asked the same questions. Most don't consider the lubricant in a manual transmission to be particularly stressed, like in an engine--with shear forces and fuel/water and other contamination--or the fluid in an automatic transmission, or in a differential, where the shear forces tend to heat the oil to extremes. Most automatics, esp. when used for towing have a fluid cooler, often embedded in the radiator, and a good 'track car' will probably have a differential cooler (my otherwise high-performance Mustang is limited on the track because of this). That's why pretty much any decent lubricant, including ATF, a good dino oil or synthetic will work fine in a manual transmission car. The OD may have some special requirement, maybe for proper friction on the cone clutch, but I've not heard of any particular fluid causing problems. Nor does a manual gearbox require multi-vis oil with a wide viscosity spread; oils like 0W-30, 5W-50, etc. aren't necessary because there is no need to move the oil to an engine top end at startup, for example. I think one advantage of a multi-vis with a small viscosity spread, like MT-90, which is rated 75W-90, is that is will retain its viscosity as the box heats up and clearances become greater (I noticed when I first installed it that the OD seemed to engage a bit quicker when hot).

So, I think the answer as to why there aren't any scientific studies on gearbox requirements is that they aren't critical, any good oil will work (even vegetable oil from your kitchen, for a few miles anyway). It comes down to 'operator impression,' and I like full-synthetics in my gearboxes but--not necessarily in engines because that oil gets changed often--and I know that a good synthetic is good for 50K miles or more. Note there is one exception: warranties. First thing I did for my Mustang, with a manual transmission that is not held in high regard by most, was to put a good full-syn oil in, and it specifically met the specs from Ford so, hopefully, there will be no warranty issues. My old Ford tractors call for GL-1 for their hydraulics and gearboxes, and I had to special order some but, in hindsight, it probably wasn't necessary (GL-1 was probably what was available in 195X).

You can only see parts of some of the gears, but here's what my BJ8's gearbox looked like with original gears at about 200K miles:

 

[Bob_Spidell]

I had the larger accumulator installed in my OD when it was rebuilt. With SAE 30 in the trans, the OD would shift rather harshly. I now have 20W/50 and, while quicker than original, it is more gentile and leaks less.

When I rebuilt my gearbox/OD I installed the DWR 'uprated' accumulator (without the insert that slows and softens engagement). I didn't notice it being particularly harsher than before; however, having seen how the OD works and its components I changed my engagement procedure. Before, I'd just flip the switch and wait for the sound and RPM change, and on disengagement I would press the clutch pedal in a couple inches to reduce the reverse torque 'shock' (yes, I know that is the point of the throttle switch). Now, I push the pedal in the same amount when engaging the OD, the transition is silky smooth and I only know the OD is engaged because of the RPM drop (at the same speed). The OD uses a cone clutch to lock the sun gear and release the planetaries to start overrunning. If you don't unload the drivetrain when sifting into OD the effect is pretty much the same as your foot accidentally slipping off the clutch pedal when you upshift; i.e. it jerks. For whatever reasons, my cone clutch had plenty of service life left--maybe 100K miles or more--at 200K miles and new ones aren't readily available, so I figure my technique is at least adequate.

 

[twas_brillig]

It's been probably five years since I put together my personal list of what Red-Line fluids to use in which LBC body parts, so I'll reiterate two things: (1) go with Red Line, and (2) check their web-pages or phone them to see what their current recommendations. ANd when I say 'Red Line': they're the guys I use; I'm sure there's other manufacturers with great products, but the advice is the same: check their web-page; phone them for their current recommendations. With a third proviso: if there's no answer, go to someone else. There's all sorts of trade-offs the producers of lubricants look at (most of which are beyond my ken). Doug