Hello,
I have not long ago purchased a 1961 Mk2 with a 240 engine fitted, it is RHD and with overdrive.
Thanks to all the contributors to this forum which I have been reading for some time. I will have a non-urgent query about two mystery, unused object behind the dashboard when I can pluck up courage to try to add photos to a post!
In the meantime, I'm sure that I saw a reference to using engine oil (20/50?) in the gearbox, but the owners handbook, Haynes etc. state EP90 hypoid gear oil. Have I got this wrong, if not then why engine oil?
Thanks,
Richard

 

Richard, The question is: does it have the 240 all-synchro gearbox as well as the engine? The original advice from Jaguar is SAE 30 for engine oil the old Moss gearbox and EP 90 for the later all synch. Beyond that, everyone has an opinion ....

The 240 gearbox is a very desirable device. It has excellent ratios for any Mk2 for a more sporting drive.

 

No sychr on 1st, so presumably an older box. So I should be using SAE 30 engine oil (not so common nowadays)?

 

That is a Moss box if the 1st gear whines & has no synchro. SAE 30 engine oil is correct.

 

Glyn, I know you are not a fan of the third party oil blenders, but I have had great success with a Moss box going from an SAE 30 engine oil to the Redline MTL oil, intended as a replacement for 30 wt oil in manual gearboxes. The syncro operation went from essentially non-existent to actually usable. Second gear syncro was slow (up from nothing!), the third and fourth were vastly improved. It transformed the driving experience for me.

I don't know if a synthetic 30 wt engine oil would have done the same thing.

 

FYI
I have a moss box in my MK1 and an all-synchro box in my MK2.
The easiest way to discriminate between a moss box and an all-synchro box is the position of reverse gear.
In a moss box is hard left and forward ie to the front of the car.
In an all-synchro box it is hard left and back ie to the rear end of the car.
​​​​​​​Cheers

 

Redline is a bit of a scam but if you are happy with it it will do no harm unless you have OD. I would not want that stuff near an OD cone clutch etc. Rather use a synthetic SAE 30. You could also move to an SAE 20 Synthetic in your climate or in general. And yes ~ stick to the majors with the development budgets.

 

I did not have OD, it was a 4 speed in an E Type.

Do you think that a synthetic engine oil would have achieved the same improved syncro action? Redline certainly made a very noticable difference in my car. Later I changed to an all syncro box and changing from a 90wt gear oil to the Redline equivalent didn't make much difference.

 

A synthetic would make a difference as would a drop in viscosity. Was it worse cold than fully warmed up?

 

I think we, or at least I, would appreciate a more extensive discussion on the requirements of gearbox, overdrive, and automatic transmission oils.

 

I hear you Peter but it would be one hell of a long one. I could write on the subject for days. There are so many variables. It would have to be done in bite size chunks & I'm not long-winded as you have no doubt noted. It all starts with what unit we are discussing & condition, then viscometric effects then moves onto additives etc. What you would understand would be easy. What Joe Bloggs would understand would be another matter. e.g. Moss box ~ question 1 ~ what is the state of the synchro cones?

 

Many thanks for your replies, I will therefore use 30 SAE engine oil.

 

A follow question on the gearbox oils..............

My3.8 MK2 has a Moss box and OD, and it for sure currently had gear lube in it, did the smell test. Yet it seems based on this and other searches, it is suppose to have 30wt motor oil instead. I just recently purchased the car and that is what I got, and it looks extremely clean like it was just changed right before the purchase.

So can I keep using the car with that gear lube? Any downside to doing so, like any internal accelerated wear, etc. I would think the Moss box might be a bit harder to shift with the thicker gear lube, but if there is know damage being done, I can live with that for now.

I will indeed change it to 30wt in the future.

So whats the consensus? Leave the gear lube in for now, OR change it immediately???

Thanks
jjsandsms

 

Also did the 'smell test' and found that it had gear oil in it, changed for Castrol XL30. Didn't notice any difference when driving, but prefer to know that I have the correct oil in it.
Incidentally, when I changed the gearbox/OD oil in my 1975 MGB GT it was advised to fill gearbox then drive car so as to refill OD, then check oil level and top up if required; it did need topping up. I adopted the same proceedure for the Jaguar with Moss box and OD but no topping up was required (in fact oil ran out, perhaps due to thermal expansion). Maybe OD fills fully when gearbox filled with this Moss/OD combination?

 

I suspect that leaving the gear oil in the box for now may not have any consequences, if it is GL4, BUT I do not know what type of gear oil it is. Could have someone actually put in GL5 oil which I believe is a big no-no! Not sure if there is a difference in "smell" between GL4 and GL5 oils? So I am going to use

Valvoline Non-Detergent Conventional SAE 30 Motor Oil:.

Still however waiting on others to offer opinions.

Thanks
jjsandsms

 

There is no difference in smell between GL4 & GL5 ~ both smell strongly of sulphur from the Sulphur Phosphorus additive they have in them. Whereas engine oil just smells of oil ~ no additive in engine oil has the pungent smell of Sulphur Phosphorus. The difference is easily detected.

Engine and SP gear oil should on no account be mixed in even slight quantity as this will cause severe air entrainment and foaming to the degree that foam will likely push it's way out of the breather. Air is a poor lubricant in other than a high pressure air bearing such as that on the tone arm of a high end turntable.

Moss Box = SAE 30 engine oil (detergeant makes no difference in fact a positive with antiwear agents such as Zinc. Remember it has cams & valvetrain to protect ~ an arduous task)
Jaguar all synchro box = GL4 SAE 90 ~ 75W-90 & 80/85W-90 also fine. An SAE 75W-90 will give easier gear change until the oil in the gearbox warms up & especially in cold climates.

GL5 Oils above approx 90 deg C will do severe damage to yellow metal synchro cones.

 

Refresh page for minor edits.

 

The Moss box definitely has yellow metal bushes and thrust washers that can suffer wear from excessive exposure to EP additives.

Another (amusing?) problem with foam (bubbly liquids) is that it's just about impossible to pump.

 

I also meant to say that today thinking has changed by the industry. We run "clean gear" technology with quite a heavy dose of detergeant in gear oils. So when you change/drain gear oil all the oxidation by-products, dirt and debris is held in suspension & comes out of whatever compartment when you change the gear oil.

 

Glyn, You have prompted the obvious question. Are gear oil detergents and engine oil detergents the same? If not, might engine oil detergent have negative effects in a gearbox?