Which gearbox oil grade

[simonjrwinter]

Many years since I changed my gearbox oil (although it looked golden and perfect when it came out) I seem to remember that 20W/50 was recommended to use with an o/d gearbox (or have I mis-remembered?)

thanks

simon

[Red6]

Just replaced my gearbox/overdrive and differential oil. My 'old school' preference was Castrol Classic EP90. Gearbox and overdrive are working perfectly.

[Tim T]

I use Penrite GB40 in both the 5 and 3a, all seems fine!

Tim

[BlueTR3A-5EKT]

26 minutes ago, Tim T said:

I use Penrite GB40 in both the 5 and 3a, all seems fine!

Tim

+1

[Tom Chatterley- Cox]

39 minutes ago, Tim T said:

I use Penrite GB40 in both the 5 and 3a, all seems fine!

Tim

+1 as well. We always recommend this to our customers.

[iain]

+1 

 

[RogerH]

2 hours ago, simonjrwinter said:

Many years since I changed my gearbox oil (although it looked golden and perfect when it came out) I seem to remember that 20W/50 was recommended to use with an o/d gearbox (or have I mis-remembered?)

thanks

simon

Hi Simon

your 20W/50 is apprx 40grade.   So go with the Penrite GB40.

But in truth there is not just one good oil.

Do not use 20W/50 engine oil - it may froth.

 

Roger

[BlueTR3A-5EKT]

2 minutes ago, RogerH said:

Hi Simon

your 20W/50 is apprx 40grade.   So go with the Penrite GB40.

But in truth there is not just one good oil.

Do not use 20W/50 engine oil - it may froth.

 

Roger

20/50 was our go to oil in the 70’s

2 gallons of Duckhams plus a filter would service the TR engine and gearbox every 3 months or 3000 miles.

 

[ntc]

Driven well over 150k in Tr’s using 20/50 as recommended by those that really know there stuff and never had any problems 

[Andy Moltu]

If you do use 20/50 you should replace every 2 years as some of the viscosity modifiers get broken down by the shearing action of the gears. 

Not an issue of you don't skimp.

The Minis, Metros etc had gearboxes in their sumps and used 20/50.

[simonjrwinter]

I have 2ltrs of Penrith GB40 on the shelf, I think that’s what I’ll use. Thanks all. 
simon

[astontr6]

14 hours ago, simonjrwinter said:

Many years since I changed my gearbox oil (although it looked golden and perfect when it came out) I seem to remember that 20W/50 was recommended to use with an o/d gearbox (or have I mis-remembered?)

thanks

simon

If you use engine oil make sure that it has the hypoid additive as the BL mini oil had! like Castrolite.  Hypoid cut gear teeth as per TR gearbox need a Hypoid base oil. Hence 80/90 hypoid recommended by BL Brown Book.

Bruce

[Drewmotty]

Engine oil is for engines. It has detergent in it to remove products of combustion and tends to foam at the lower temperatures which a gearbox sees and cause overdrive actuation problems. Unlike gearbox oil it is designed to be changed regularly. anything with a high pressure additive (Hypiod) will be less than ideal for an overdrive unit.

I've tested a few different oils with a bench run gearbox and overdrive so my observations are not based on "what the bloke down the pub said" :-)

I use Penrite GB40.

[RogerH]

33 minutes ago, astontr6 said:

If you use engine oil make sure that it has the hypoid additive as the BL mini oil had! like Castrolite.  Hypoid cut gear teeth as per TR gearbox need a Hypoid base oil. Hence 80/90 hypoid recommended by BL Brown Book.

Bruce

Hi Bruce,

the gears in the TR GB are not Hypoid, they are helix.

Whereas a Hypoid has a sliding action tooth on tooth the helix has a rolling action.

In the early days of the OD EP oils were noy recommended as the heat from the internal clutch could break the oil down and solid particles could clog things up.

In the mid 60's EP was then recommended probably to reduce leaking.

The Mini GB was a different kettle of fish.

 

Roger

Edited July 23, 2022 by RogerH

[Mike C]

5 minutes ago, RogerH said:

Hi Bruce,

the gears in the TR GB are not Hypoid, they a helix.

Whereas a Hypoid has a sliding action tooth on tooth the helix has a rolling action.

In the early days of the OD EP oils were noy recommended as the heat from the internal clutch could break the oil down and solid particles could clog things up.

In the mid 60's EP was then recommended probably to reduce leaking.

The Mini GB was a different kettle of fish.

 

Roger

+1. The sliding friction additives in GL5 hypoid oils rendered my synchro's pretty useless for fast changes.

[astontr6]

9 minutes ago, Drewmotty said:

Engine oil is for engines. It has detergent in it to remove products of combustion and tends to foam at the lower temperatures which a gearbox sees and cause overdrive actuation problems. Unlike gearbox oil it is designed to be changed regularly. anything with a high pressure additive (Hypiod) will be less than ideal for an overdrive unit.

I've tested a few different oils with a bench run gearbox and overdrive so my observations are not based on "what the bloke down the pub said" :-)

I use Penrite GB40.

Are you saying that the Brown book is wrong

 

1 minute ago, RogerH said:

Hi Bruce,

the gears in the TR GB are not Hypoid, they a helix.

Whereas a Hypoid has a sliding action tooth on tooth the helix has a rolling action.

In the early days of the OD EP oils were noy recommended as the heat from the internal clutch could break the oil down and solid particles could clog things up.

In the mid 60's EP was then recommended probably to reduce leaking.

The Mini GB was a different kettle of fish.

 

Roger

I was always told by BL competition Dept.  that they had gone over to Hypoid machined teeth which incorporated the machining of the helix as well and had to buy new plant. Reason: this enables the G/B teeth to take more power and better engagement and cut down the likely hood of the orange peel effect on the teeth.

Bruce.

[RogerH]

Hi Bruce,

 that may be so for the mini as it had a combined GB and diff.

But the Hypoid gear design was purely for the diff in order to save space,  The Hypoid gear set up for the equivalent Bevel gear set up.

Roger

[astontr6]

49 minutes ago, Drewmotty said:

Engine oil is for engines. It has detergent in it to remove products of combustion and tends to foam at the lower temperatures which a gearbox sees and cause overdrive actuation problems. Unlike gearbox oil it is designed to be changed regularly. anything with a high pressure additive (Hypiod) will be less than ideal for an overdrive unit.

I've tested a few different oils with a bench run gearbox and overdrive so my observations are not based on "what the bloke down the pub said" :-)

I use Penrite GB40.

The foaming of engine oil is caused by the oil not having the hypoid additive in it as it breaks down. There were 2 members of our TR group who had this problem and it cause their O/Ds to malfunction. Then the G/B had to be stripped down and cleaned out. The cost was not far short £1000 per box.

They were not happy campers.

Bruce.

[simonjrwinter]

Well, I had some Penrite GB40 and that’s the one that’s gone in….seems fine (although only got about 1.5 litres in before it started to overflow, having been left overnight to drain)

Edited July 23, 2022 by simonjrwinter

[Drewmotty]

“Are you saying that the Brown book is wrong?”

…..Things may have changed since the book was written but as I see it today: Yes. As always I’m happy to be put right…..I’m still learning every day :-)

It may be of interest that all the oils I tested including GB40 foamed to varying degrees at working temperatures below about 30 degC. Bearing in mind that it takes a lot longer for the gearbox to heat up than it does the engine it may be prudent to drive gently until things are well warmed through. 

Edited July 23, 2022 by Drewmotty

[Hamish]

17 hours ago, Tom Chatterley- Cox said:

+1 as well. We always recommend this to our customers.

Gear 40 in mine with A type OD

Works from ambient temps straight away unload from trailer and then sprint - 

not that I abuse my gear box much 

[BlueTR3A-5EKT]

Many years ago the rep from Castrol in his enthusiasm to sell us oil for the shop took away our need for a suitable oil for TR gearboxes with overdrive and came back with the recommendation from their technical department of Castrol ST90.  Their recommendations we took as helpful as up to then there was always conflicting service manual information.  
Castrol ST90 is a GL3 straight 90 weight gear oil without EP additives.   Used mostly by motorcycles with wet clutches (overdrive clutch) and helical gears (TR gears)

We used to sell a lot of the stuff along with B373 for plate type LSD.

Never sold much EP90 or GTX as it was always cheaper in Halfords.

Peter W

[michaelfinnis]

The original Triumph workshop manual  recommends BP Gear Oil 90EP, Castrol Hypoy and Duckhams Hypoid 90 among others. Where did a recommendation for engine oil come from, and why the concern about using EP grade Hypoid oils?

I appreciate that there may be modern oils that are suitable or better alternatives.

Mike.

 

[RogerH]

Hi Mike,

Which Original Workshop manual - TR2, 3, 3A, 4, 4A 5 or 6

The early cars specified non-EP oils due to the yellow metals.

The TR4A did specify EP  But a GL4 should be used.

I don't think engine oil was ever specified. Can you have a 20/50 non engine oil.!!!

 

Roger 

[Drewmotty]

20w/50 was specified for MGBs with overdrive gearboxes. I’d be interested to know who specified it and why.