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MG Midget and Sprite Technical - oil viscosity

The book for my 76 midget 1500 says I should use 20w/40 or 20w/50 motor oil. I am having a hard time finding these. Are they available and if not what other viscosity can be used. Thanks for any thoughts.

You can't go wrong with any brand of 20W50, 20W40 may be a little too thin.

I personally use Valvoline Racing VR1 20W50 because it's one of the last remaining oils to have ZDDP in it (an additive that's important for older engines).

Any of your local automotive parts stores should carry 20W50, I get mine at Autozone, Advance, Pep Boys, NAPA or O'Reilly. Probably Walmart too, but I haven't checked there.
Dave Rhine ('78 1500)

I agree with Dave,need 50w AND zddp,so VR1 is the choice,even if a bit expensive and hard to find.
steve cowling

How about Castrol classic or Millers classic? Good oils for our cars IMHO, including the zddp.
Alex G Matla

Yep, they need ZDDP.

I wasn't aware of the lack of it in modern oils until a couple years ago.

I have a some buddies who own classic muscle cars from the 60's...they educated me on the need, but at that time, all of my cars were more modern & didn't need it.

I'm not sure if Castrol Classic is available stateside, when I first bought my car I did a little browsing & all I remember seeing was availability in the UK, Valvoline VR1 is in all my local parts stores.
Dave Rhine ('78 1500)

Thanks for the help. I went to three auto stores and finally found the 20/50 valvoline racing oil. It does contain ZDDP. I will change it out tomorrow.

There you go, all set!
Dave Rhine ('78 1500)

The oil conversations get complicated quick. Something to keep in mind about VR1 : it may not contain the same amount of detergents as regular oils. I'm currently using VR1, but my oil changes are occurring at about 1500 miles. When I start driving more, I'll need to look for other solutions.
Trevor Jessie

Yep, lack of detergents may be a concern, I read up on it a little over the winter.

I change my oil seasonally, so not a concern for me at this time.
Dave Rhine ('78 1500)

What the heck is ZDDP???
Up to now used standard 15/50 oil (couldn't find the 20/50) but apparently this is very wrong.

Ben (learning every day from this BBS)
B Elfrink

Ben, it's a zink-phosphate compound, added to prevent pitting of the cam followers. It helps the oil resist higher pressures.
There are other issues involved with this additive, for instance it has an influence on the detergents added.
Alex G Matla

I went to Halfords today and found they still sell "Classic Motor Oil" 20w50. It has a Midget on the tin and it smells like my Granddad's garage! and it only cost as much as a few beers. I also bought a can of Wynns engine flush. However, before I use it, are there any possible problems that this stuff can cause? My car is my little friend and I would hate to make it feel ill.

N Sayle

There is also ZDDP additive available separately but I prefer to use oil that already has it. The reason is that it seems that a good amount is around .120% by volume. That is not much. From what I have read it also seems that .160% or more can cause damage also. Because of the small amount by volume I would not feel confident measuring the correct to add.

Barney Gaylord ( swears by 10W40 for MGAs. Not too thick for colder climes but thick enough for hot weather. 50 weight just makes the oil pump work harder. I'll be moving to 10W40 for my 1275 Midget.

Correct me if I'm wrong: ZDDP is only necessary for cam break in. However, there's an oil that truckers use (can't think of it off the top of my head but it's available at all auto parts stores) that contains ZDDP. I'll be looking for that when I change to 10W40.
JM Morris

There has been much written on this subject of late on forums and on the web. I used to buy oil at Auto Zone that was a store brand with a label that ended in L. This hada enough zinc in the oil. The latest rating ends in M and this doesn't have the correct amount of zinc to protect our motors. I was at Auto Zone yesterday and that store brand is now rated M. Your choices are a classic rated oil or adding ZDDP. Putting modern oil in are old cars isn't good. Do some Google searching to get more info.
J Bubela

I've recalled the trucker's oil--Rotella!
JM Morris


My understanding is the lack of ZDDP will make the cam & lifters wear prematurely.

It was removed from modern oils because it will stop up catalytic converters.

I'm taking no chances, if these engines were designed to have ZDDP in the oil, I'm using oil with it or adding some.

Check out this website:
Dave Rhine ('78 1500)

Oops forgot to add: click on the techical tab for a good explaination.
Dave Rhine ('78 1500)

ZDDP is required to prevent premature wear on flat face lifters (tappets) as fitted to '60s and '70s nOHV engines.

It has far less/zero effect on OHC lifters (owing to their radiused design).

Dave is correct in stating that it was removed from modern oils because it poisons catalytic converters.

WRT to the Triumph 1500 lump, you MUST use a good 20/50 (and Valvoline VR1 Racing is what I recommend). For 'tuned' motors I would use a 20/60 such as Penrite.
Deborah Evans

If you have to buy a pint at the local petrol station and can't get the proper "classic" oil then get "diesel" oil.
they have no catalytic convertors and have more ZDDP (less then the proper stuff but still)
Onno Könemann

Duckhams Classic 20W50

Almost every motor spares place will keep it.

There was a test done a few years ago now where all the fancy oils were tested in a B-series engine.

The winner by a fair margin happened to be a cheap as chips supermarket 20W50 oil which caused the least wear on the mechanical parts of the engine.

All of our competition cars run on Duckhams Classic though with no additives.

There is no requirement to over complicate it or use fancy expensive oils such as the Castrol Edge, etc.

PJ Moore

This thread was discussed between 22/03/2010 and 24/03/2010

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