oil for differential

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bobs12tourer
Posts: 5
Joined: Thu Mar 11, 2021 11:54 am

oil for differential

Post by bobs12tourer » Wed Apr 21, 2021 12:38 pm

Morning folks

I have just drained the oil from my 47 - 12 Tourer & just over 3 litres came out. Just like black treacle as I have had it 45 years & am now renovating !!
In the workshop manual its say 2 litres should be in there ? So how much do I put in & is a modern diff oil OK or should any other special type of diff oil be used ?

Also I will be putting new oil in gearbox & engine so same ask re quantities & type please.

Many thanks Bob

TonyG
Posts: 288
Joined: Mon Sep 07, 2015 4:38 pm

Re: oil for differential

Post by TonyG » Thu Apr 22, 2021 6:49 pm

Hi Bob,

My pre War cars are supposed to have SAE 30 in the engine, SAE40 in the gearbox and either SAE40 or 50 in the back axle. So, I’m assuming your car is the same. The key thing is to use Classic oils rather than modern ones, which contain additives that might attack the yellow metals used in our cars. Also, modern engine oils are designed to hold the dirt and metal particles in suspension for filtering when pumped through the filter. However, our cars do not have a filter, other than the gauze pick-up filter in the sump, so it’s best to have an oil that doesn’t hold the bits and let’s them collect in the sump.

Of course, preWar, there were no multi grade oils available so a Classic 20/50 is probably a good bet for the engine. Castrol do a range of Classic oils, available from most motorist shops. Comma also do some, which are a bit cheaper. Other suppliers like Penrite also do a range of Classic oils but these are rarely stocked by local suppliers.

Recently I have been undertaking work on a couple of old tractors, one early 50s and the other early 60s. Both are diesel and should use SAE 30,40 and 50 like our cars. I found a company on-line called Rye Oils who supply Classic oils of this type in 25L drums for around £50 each. They also do a Classic 20/50. Given that most old Rovers won’t go very far between services and their lack of filtering capability I think I will start using these oils for my cars. At £2 per litre it’s less than half the price of the premium brands mentioned above.

Regarding capacity, your engine takes about a gallon and the gearbox about 2 pints. Both have dip sticks to check though. The back axle should be filled to the level of the filler plug. If you had more than expected in it maybe the car was jacked up on one side when it was filled?

We are all very careful to put the specified oils in our cars but I suspect they have had all sorts of oils and grades put in during their working lives. When I drained my Saloon axle for the first time the oil was so thick it was more like grease, no doubt to keep it quiet!

Hope that helps a bit.

Tony.
Tony Gilbert

P1 12 Tourer
P2 12 6 Light Saloon
Discovery 3
Discovery Sport

bobs12tourer
Posts: 5
Joined: Thu Mar 11, 2021 11:54 am

Re: oil for differential

Post by bobs12tourer » Thu Apr 22, 2021 10:57 pm

Hi Tony Many thanks for your information which I will take on board.
I am local to Morris Oils in Shrewsbury so armed with your information I will ask them about their classic oil range. I use their oils for my Harley Davidson motorbikes which is more cost effective & better I think than original Harley Davidson oil.

again many thanks Bob

David2021
Posts: 231
Joined: Sun Jan 31, 2021 4:29 pm
Location: Stratford upon Avon

Re: oil for differential

Post by David2021 » Tue Apr 27, 2021 1:38 pm

In my Austin Sevens (1927-1932) I use Castrol EP140 in the back axle and a straight SAE30 in gearbox & engine sold as "Lawn Mower oil!" Around £18 for 5 litres delivered Amazon! RocWood. There are others!

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