[racing] EP90 GL4 and GL5 + 20/50

Racing
1

Hello, my racing friends, I normally only post in Saloons.
But I suspect this subject may get some answers from you
guys! If anyone knows you will!
(my car for the record is a manual syncro 3.8 S-type
overdrive)

Apologies for re-visiting this EP90 GL4 and GL5 + 20/50

Does anyone actually know the correct answer? I’m not sure
there is a single correct answer?

So, according to the Jaguar manual it says early non syncro
gearboxes, should have 20/50 (or in those days 30SAE).
It then says at the end of the chapter later cars with
syncro should have EP 90. (or 80/90 these days)

Ok simple? Err no. So EP90 (or EP 80/90 as it now is ) is
available in GL4 and GL5, this just means the amount of
additives in it (lets not confuse the semi synthetic
qualities with the GL raiting).
However use EP90 GL5 in a car with brass bearings and you
will have trouble. GL4 is (according to Halfords printed in
store guide) gearbox oil and GL5 rear diff oil. I can also
see the landrover / Trumpy guys need GL4 not GL5. However
im not sure what a Jagaur needs and if it has the bearing
affected in the box by GL5… But I now think GL4 is correct
for Jaguar not GL5…

Now lets add the curve ball in. When I had my syncro
gearbox and laycock overdrive rebuilt (very big and
reputable company) the guy said use 20/50 not EP 90 or it
will burn the overdrive clutch cone. I have been googling
this and many many people are sayign the same thing that
laycock overdrive’s don’t like EP90.

So I go to Pentire Oil’s home page… For a MK2 (Mine is a
S-type) they recommend their Gear oil 30, NOT EP 90… (for
all years including overdrive). Infact they say that you
should not use EP90 in a laycock overdrive, and this is from
Pentite…
http://www.angloparts.com/images_ap/newsletter/Penrite_broch
ure.pdf

So go to Millers and they say EP90!!! (and apparently its
good for overdrives!)
http://www.millersoils.net/1_Millers_frame_CLASSIC.htm

So depending where you look each answer is correct. Even
GL5…

EP90 GL4

EP90 GL5

20/50 / SAE30

Roll the dice and stick it in…

I was going to use EP90 GL5, but I now believe that is
totally wrong. I then thought EP80/90 GL4, but I am now
thinking 20/50!!!

The answer �just do what it says in the Jaguar manual� I
believe is incorrect because they may not have known that
EP90 burned the overdrive cones with the shared oil from the
gearbox. (they were never built by Jaguar) Also early boxes
used 20/50 so why cant that be used on a later box, because
we know syncros are not damaged with out EP90…

NIGHTMARE.

Anyone have any cold hard facts?–
Lusstor
UK - South, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

//please trim quoted text to context only

2

Lusstor;
I’m looking at the commission plate from a 1960 Mk2 with OD. The tag clearly
states (in pre-new nomenclature format) Mobiloil A, Castrol XXL, Shell x-100
30, Esso Extra 20W/30, Energol 30 and lastly, SAE 30. Hypoid oils are
recommended for the differential. It is for real that the high viscosity,
extreme pressure oils will cause the cone clutch to slip and overheat. I’ve
personally ruined two ODs with the stuff.
Bob Grossman-----Original Message-----
From: owner-racing@jag-lovers.org [mailto:owner-racing@jag-lovers.org] On
Behalf Of Lusstor
Sent: Sunday, January 30, 2011 1:07 AM
To: racing@jag-lovers.org
Subject: [racing] EP90 GL4 and GL5 + 20/50

Hello, my racing friends, I normally only post in Saloons.
But I suspect this subject may get some answers from you
guys! If anyone knows you will!
(my car for the record is a manual syncro 3.8 S-type
overdrive)

Apologies for re-visiting this EP90 GL4 and GL5 + 20/50

Does anyone actually know the correct answer? I’m not sure
there is a single correct answer?

So, according to the Jaguar manual it says early non syncro
gearboxes, should have 20/50 (or in those days 30SAE).
It then says at the end of the chapter later cars with
syncro should have EP 90. (or 80/90 these days)

Ok simple? Err no. So EP90 (or EP 80/90 as it now is ) is
available in GL4 and GL5, this just means the amount of
additives in it (lets not confuse the semi synthetic
qualities with the GL raiting).
However use EP90 GL5 in a car with brass bearings and you
will have trouble. GL4 is (according to Halfords printed in
store guide) gearbox oil and GL5 rear diff oil. I can also
see the landrover / Trumpy guys need GL4 not GL5. However
im not sure what a Jagaur needs and if it has the bearing
affected in the box by GL5… But I now think GL4 is correct
for Jaguar not GL5…

Now lets add the curve ball in. When I had my syncro
gearbox and laycock overdrive rebuilt (very big and
reputable company) the guy said use 20/50 not EP 90 or it
will burn the overdrive clutch cone. I have been googling
this and many many people are sayign the same thing that
laycock overdrive’s don’t like EP90.

So I go to Pentire Oil’s home page… For a MK2 (Mine is a
S-type) they recommend their Gear oil 30, NOT EP 90… (for
all years including overdrive). Infact they say that you
should not use EP90 in a laycock overdrive, and this is from
Pentite…
http://www.angloparts.com/images_ap/newsletter/Penrite_broch
ure.pdf

//please trim quoted text to context only

3

In reply to a message from Robert Grossman sent Sun 30 Jan 2011:

Is that an early non syncro? I suspect 1960 would be, so
20/50 is correct. However if that were a late car it should
be (according the the manual) EP90…

But yes, I am hearing lots of people say EP90 runs clutch
cones on overdrives… so why did Jaguar reccomend it in the
service manual!!! ;-)–
The original message included these comments:

I’m looking at the commission plate from a 1960 Mk2 with OD. The tag clearly
So, according to the Jaguar manual it says early non syncro
gearboxes, should have 20/50 (or in those days 30SAE).

–
Lusstor
UK - South, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

//please trim quoted text to context only

4

In reply to a message from Robert Grossman sent Sun 30 Jan 2011:

Is that an early non syncro? I suspect 1960 would be, so
20/50 is correct. However if that were a late car it should
be (according the the manual) EP90…

But yes, I am hearing lots of people say EP90 runs clutch
cones on overdrives… so why did Jaguar reccomend it in the
service manual!!! :wink:
GL-5 gear oil is designed for large displacement hypoids, i.e. very high
pressure applications. At least for a conventional oil, this means it
has around double the amount of sulphur high pressure additives than do
GL-4. This sulphur in high concentrations can attack bronze etc, so it
can as such be a problem not only for ODs, but even synchro rings. Note
that synthetic gear oils may not contain very much sulphur at all, even
for the GL-5 rating, so they may be more compatible with bronze.

Another effect of high pressure additives by their virtue may cause to
OD cone clutch to slip. I am not aware of any tests for this effect in
the rating system, however.

Back in the 60s, EP90 would surely mean GL-4, and of course there were
no synthetics at the time.

The advice I got from Mobil many years ago was that for a /Laycock de
Normanville/ overdrive, GL-4 was OK, but GL-5 was not recommended.

So if using gear oil I would definitely made sure I used GL-4, and
absolutely avoided anything GL-5. I also believe multigrade synthetic
gear oil is a good choice if low temperatures are encountered; I doubt
the OD is very happy at all pumping around the molasses-like consistence
of conventional oils.

That said, I am also pretty certain that modern motor oils most probably
easily satisfy the lubrication requirements of an old Jaguar gearboxes.

Egil

//please trim quoted text to context onlyOn 01/31/2011 10:02 AM, Lusstor wrote:

5

In reply to a message from Egil Kvaleberg sent Mon 31 Jan 2011:

Egil.

Thanks. Just for your interest.

They have done some testing…

http://www.quantumechanics.com/categories.php?op=newindex&catid=11

I think even though it says for my car EP90 I am going to use 20/50
or 30 SAE… To protect the overdrive. Apparently the box runs fine
on 20/50… Thats what people use on the moss boxes, so I cant
believe its not the right oil for the later boxes!!!–
Lusstor
UK - South, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

//please trim quoted text to context only

6

I am going through this exact issue.
The Jag all-synchro seems to need hypoid EP oil (but why?) and that oil (or modern equivalent) might be bad for the O/D.
What did you do in the end? how did it go?