MGB Gearbox Transmission Oil Change in a Chrome Bumper Pre-1974 Car

A quick video covering how to check and change the gearbox oil in an MGB. The car I am working on is a pre-1974 (chrome bumper) with the gearbox filler behind the speaker housing, on later cars the oil filler is on the side of the gearbox and accessed underneath the car.
The oil syringe I am using can be found here www.opieoils.co.uk/p-144494-l... . The gearbox oil is Castrol Classic 20/50 and is available here www.opieoils.co.uk/p-77263-ca...
For a 4 synchro non-overdrive gearbox you will need just over 2.5 litres of oil, for an overdrive gearbox you will need just over 3.3 litres. It is worth checking the gearbox oil again after the car has run for a short distance. One should aim to have the oil right on the high level marker on the dipstick.
The general consensus seems to be to change the transmission fluid every 25,000 miles in a road car. If you are using the car for track days, I would certainly recommend changing the oi every year. I was surprised by the amount of small metal shavings in my gearbox after around 4 hours of track time.
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[@tedsmith_photography]

Ha...you are a man of your word! (David and I exchanged e-mails a while ago and he promised he would do this one). Great to see that even you find this to be a fiddle of a job. Like I said in our e-mails, I also bought a syringe type tool after first trying with a stretch of pipe and a funnel, though mine was a "2 tube system"...one goes in the oil can, and the other into the destination, and then you pump and the oil travel from source to destination. Tip for others : always be certain your tube is actually IN the hole! I started pumping only to find the pipe was sitting on top of the gear box and not IN the gear box! Pumped about half a lite onto the driveway!! A wish I'd realised those bristles on the plug are actually to be removed! I didn't realise they were sharded bits of metal! There was a few left on mine when I put it back in. I'll have to endeavour to clean it off properly next time. Thanks David...great as ever.

[@davidrussellwilks]

TED SMITH Many thanks for your kind message Ted, glad that you enjoyed the video. I’ve been there before with a tube that wasn’t quite lined up with the hole in the gearbox and squirted oil all over the garage floor. Hope that everything is good with you.

[@MorroccoM13]

Years ago I found a metal funnel with a flexible metal hose. Its just the right size to get into that tight spot. Thanks for another great video.

[@MGB-learning]

Outstanding video and presentation.

[@davidrussellwilks]

Many thanks

[@philga1]

Loving the simple but oh so useful tip of the zip tie through the top of the dip stick!

[@davidrussellwilks]

Glad it was helpful!

[@dorisjung5147]

Spur Videos helfend me very much, to learn a lot about how my MGB works. Thank You!

[@gjones455]

Great video, really informative, thanks for taking the time to share it with everyone

[@davidrussellwilks]

Glad you found it useful!

[@SierraJohn]

Great video. Brings back memories of changing the gearbox oil in my MGA. Just subscribed.

[@davidrussellwilks]

Thanks for the sub!

[@robingibson7503]

Eye opener for sure!!! I have never changed the oil!!!!!

[@davidrussellwilks]

Well worth doing Robin, usually not too bad a job, refilling is the hardest part.

[@ItsaboutMakingnotBuying]

Good information I have a 1974 1/2 MGB GT. Now I know where the fill hole is for the trans. Later

[@davidrussellwilks]

Yes, it will be underneath, with the car level you can fill the transmission from the top hole until it runs out, just the same as the axle.

[@pingstudio8235]

great video, now i know here to top up ! thanks

[@davidrussellwilks]

No problem 👍

[@stevetong1576]

Many thanks for this, I bought the recommended syringe and it made the job on my 1974 (very last of the chrome) more than ‘approachable’! I was only topping up and I understand the difference between the High and Low levels is one pint (same as engine oil dipstick).

[@davidrussellwilks]

Thanks for the note on the different levels, it's easy to overfill and then have to drain a bit out. Delighted to hear the syringe tool worked for you.

[@DesAcetek]

super video

[@davidrussellwilks]

Many thanks Des!

[@philoliver3492]

Thanks Great help

[@davidrussellwilks]

You're welcome!

[@tkreitler]

I just changed mine last month and that syringe would have made it easier. The description for the syringe on the link says 14.5 liters. I believe they mean 1.45 liters. As always, thank you for taking the time and effort to make these videos.

[@davidrussellwilks]

Yes, that's correct Trent, I'm not sure one could easily lift a syringe with 14 litres of oil in it! I think it should say 1.5 litres

[@dickstagnone2765]

The magnetic drain plug is a nice update. Not that I’m racing but I got one for the oil pan, never thought of the transmission. Now I have to find one.

[@davidrussellwilks]

The one in my car came from Moss, part ref 2K5830X.

[@Jizzy342]

Thanks for the info, I was just thinking I needed to change the oil in my '72. The syringe is also £15 cheaper on amazon.

[@davidrussellwilks]

Great find on the syringe, I think there are a few companies making similar items, it certainly makes the job a lot easier.

[@Jizzy342]

@@davidrussellwilks Although true, with Laser products like the Syringe they mostly put their code on it making it easier to order through Laser. Search google for Laser 5699. Works the same for other Laser products and many other companies too.

[@johnathankain8033]

About to attempt this job on a newly acquired car (who knows when it was last done). Having a dipstick makes it nice to check levels, but it does seem like having to load oil through the passenger compartment in an awkward place, is a beautifully crazy bit of design.

[@davidrussellwilks]

In the past this used to be an incredibly messy and difficult job for me, having the oil warm and something to pump it in with does make it a whole lot easier! I think the later cars have the filler on the side and you pump the oil in until it starts coming out. I've never changed the oil in one of these cars but it might be easier?

[@praetorious]

That oil syringe is great, I'll have to get one. I've been using this tiny manual transfer pump to move the fluid from the bottle to the gearcase. The number of strokes required is inconvenient.

[@davidrussellwilks]

Two fills from the syringe and (in theory) you should be about done, I must have lost a few ml when I refilled and needed the third just to finish it off. the most messy bit is refilling after the first pour, bit if you do this in a drip tray it does keep most of the oil in one place.

[@SteveDentonClassics]

Great video as always mate. Think next time I change my gear oil on the GT, I'll be nipping over yours and borrowing your syringe, my thumb was looking like Popeye's arms after pumping it in with an oil can

[@davidrussellwilks]

you would be most welcome Steve, it certainly makes the job a lot quicker and a bit easier.

[@ricky111G]

Great video its a right pain getting to that dip stick whens its stuck in! The rear diff oil change would be a good video if you could show what tooling you would need to remove the fill plug. If you can even buy a socket to remove the fill plug that would be so handy.

[@davidrussellwilks]

Many thanks Rik, totally agree on that dipstick it can be a real pain to get out. I forgot to add that I sometimes just smear a bit of oil on the two o-rings to make removal just a bit easier. I have a whole diff video coming soon including how to replace it (this is on the earlier Banjo type, the the refill procedure is the same) I changed the drain plugs to the later type with a hex head on my car. I think for the square type plugs a 1/2 drive extension bar usually fits, there are special tools available if you need them though.

[@ricky111G]

@@davidrussellwilks Oh thats a good idea using oil on the o-rings I will now be doing that. Ill be waiting for the diff video good stuff!!

[@AdrianBellVoiceovers]

That’s an awesome video. Very well put together and good knowledge I have a 67MGB, here in Canada that I imported from Britain in the late 80s Can I assume that everything I’ve seen you do, is what I need to do on mine? Many thanks, very good instructional video.

[@davidrussellwilks]

It should be all the same Adrian. This season I've had a few issues with the gearbox synchro rings, the gearbox specialist I use for rebuilds recommended trying the Duckhams Classic Hypoid 85w-140 Gear Oil. I still continued to have the issues though! In terms of oil choice I think a standard classic 20w-50 is a good option

[@fernandolaguarda]

Dios mio!

[@garethgoodchild2643]

I'm amazed at the condition of the old oil. Racing obviously is very hard on the gear box. How often do you need to rebuild?

[@davidrussellwilks]

I have the gearbox refreshed every 2 years or sooner if the synchros break. It seems to be the synchro/baulk rings that take most of the abuse; a few years ago they were only lasting a few rounds, but more recently they have been lasting longer.

[@RichardChynoweth]

Hi David, I've just watched your steering rack lube video and ordered the EP 80W-90 to do that job. I wondered, would the EP be better for the gearbox as well? I do have a can of Castrol classic 20/50, so I could use which ever is best. Thanks for uploading all your mg knowledge. Your videos are great, and spur me on to maintain my MGB by myself.

[@davidrussellwilks]

Thanks for your message Richard, I've always stuck with the 20/50 for the gearbox, from conversations with various people this seems the preferred choice. I use the EP90 (or similar) for the rear axle.

[@RichardChynoweth]

20/50 it is then. Thank you, advice very much appreciated.

[@MrYouTuba]

Very informative. Thank you. Is the location the same for a LHD car (i.e. on the passenger side)? My MGB was built in Dec 1973 although it is technically a 74 as it was shipped to Canada in January 1974. It does have chrome bumpers.

[@davidrussellwilks]

Thanks for your message, the dipstick and fill point should be in the same place. On later cars (Rubber Bumper only I think) the gearbox filler is accesses from under the car and is on the side of the gearbox

[@desby5]

hi david i have 2 gallons of 15\40 castrol gtx will this be ok in my mgb gt many thanks

[@davidrussellwilks]

Personally I would only use a 20/50 oil, the 15/40 may be a bit thin

[@desby5]

good morning david what gearbox oil do i use in my 1979 mgb gt it has overdrive also do i need to change the filter many thanks richard

[@davidrussellwilks]

I don't know so much about the overdrive internals but I don't think you need to change the filter when you change the gearbox oil. The oil I used Castrol 20W50 will be fine for your overdrive gearbox.

[@desby5]

@@davidrussellwilks many thanks for your videos thank you for a quick reply all the best for 2021 richard

[@hankpb1]

that's a big syringe

[@martingenerous1678]

can you show a 1500

[@boratsagdiyev7900]

About to buy my first mgb gt, any tips for things to avoid whilst buying?

[@davidrussellwilks]

The number one thing to look for is rust. Bodywork is usually the most difficult and the most expensive part to repair.

[@boratsagdiyev7900]

@@davidrussellwilks Thanks David, I'm really interested in working on my own car and your channel is really helpful :)

[@jameseastwood4984]

@@boratsagdiyev7900 I have a B GT V8, I would thoroughly recommend one if the budget will permit. Feels like quite a different car and is very good at longer distances due to a high dif ratio (plus over drive). I have used it as a daily driver in the summer.

[@jameseastwood4984]

David are you racing at Zandvoort this weekend?

[@davidrussellwilks]

Unfortunately no overseas rounds this year, we ware at Snetterton this weekend though.

[@jameseastwood4984]

@@davidrussellwilks yes I understand, thanks for getting back to me. James Eastwood.

[@manekdubash5022]

@@davidrussellwilks Sorry I missed coming to the Snetterton race, David. I had planned to make the trip from the south coast but when I saw that MSV was banning visitors from the pits and paddock, it didn't seem nearly so attractive a proposition. The fun that was had at the Monza GP was a small consolation...

[@Cell1000bc]

What mechanic wears white? :). My gearbox drain leaks and drips, think I may use a smear of thread sealant next time.

[@davidrussellwilks]

The overalls are partly for the vintage look Dave but they do serve a purpose too; it's easy to see if you have a dirty backside before you sit on a nice clean seat!

[@desby5]

in my engine nearly forgot

[@davidrussellwilks]

Personally I would only use a 20/50 oil, the 15/40 may be a bit thin