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Joined: Dec 2008
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Roadster Guru
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The 75w90 grade is what I would expect to use in an MGB diff.

For the BTR I use Morris Lubricants, from memory either 75W140 or 80W140.

I don't think the fully synthetic/Semi synthetic difference matters, but it's handy to have it include friction modifier, although this can be bought and added separately.


DaveW
'05 Red Roadster S1
'16 Yellow (Not the only) Narrow AR GDI Plus 4
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Just checked, and 75w90 is the gearbox recommended grade for the more recent Plus 4.


DaveW
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'16 Yellow (Not the only) Narrow AR GDI Plus 4
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Has a lot to Say!
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Miller oils website has a handy guide to which lubricant you need, it even lists Morgan. From memory I think the back end oil was 75w 140NT+

No connection, just a happy customer.


Gordon Duguid
2014 Duratec engine plus 4, Montreal blue.
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Tricky Dicky
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https://www.mpdonline.co.uk/product...-ls-gear-oil-gl5-1lt-ls80w901l/LS80W901L

I use this product for my LSD BTR it’s the one the local boys use in their Scoobies.
Used it for 17 years now.

I use Comma lube products for every application on the Plus 8, they are good quality products at Devon (sensible) prices you can overthink lubricants.


2009 4/4 Sport Henrietta
1999 Indigo Blue +8
2009 4/4 Sport Green prev
1993 Con Green +8 prev





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Just barreling along
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Originally Posted by Gordon D
Miller oils website has a handy guide to which lubricant you need, it even lists Morgan. From memory I think the back end oil was 75w 140NT+

No connection, just a happy customer.

NT is the posh nano tech stuff, went to a talk at Millers a few years ago & NT grades are clever stuff


Jon M
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Thanks for all the contributions on this. Gordon’s & Dave’s memories correlate with Millers who along with Morgan, recommend 75w140.
To my mind, it seemed a bit heavy for a light vehicle. However, Rich is quite happy with the lighter version but as he said...you can overthink these things. Also amazing the price difference between Comma and Morris! (£8 odd vs. £20 odd)
I believe it is more important to ensure that proper LSD oil (or additives) are used in a LSD diff. to cope with shock loadings, more so than the actual viscosity.


Doug
2011 Plus 4 in Rich Maroon

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Tricky Dicky
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Originally Posted by Deejay

To my mind, it seemed a bit heavy for a light vehicle. However, Rich is quite happy with the lighter version but as he said...you can overthink these things. Also amazing the price difference between Comma and Morris! (£8 odd vs. £20 odd)
I believe it is more important to ensure that proper LSD oil (or additives) are used in a LSD diff. to cope with shock loadings, more so than the actual viscosity.

That is my thinking Deejay that on a lightweight car the standard diff grade is more than adequate but has to be LSD capable.


2009 4/4 Sport Henrietta
1999 Indigo Blue +8
2009 4/4 Sport Green prev
1993 Con Green +8 prev





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I checked the gomog +8 specific and it states SAF-XJ 1.7 ltrs . this then became syntrax 75w-140 . Now according to opioil website this has been replaced by transmax 75w-140 all castrol oil but I couldn’t find any more info regarding this change I supposed because it’s a long life oil and not something you change regular it doesn’t crop up that often

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Fus969 Offline OP
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Forgot to say mines a 97 so BTR axle Salisbury may be different

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