domino · Mar 23, 2021

So, I bought some Westway 80w90 Gear Oil - mmarked as API: GL4.

Doing a bit of searching, some people seem to suggest the P38 need GL5. Others make no mention of it. RAVE makes no mention of it and simply states "Texaco Multigear 75w 90R" - no mention of API.

What is the *correct* fluid for the front and rear diff before I open this container?

allanw · Mar 23, 2021

I have used 75/90 synthetic on Discovery's and P38's for a few years now.

domino · Mar 23, 2021

allanw said:
I have used 75/90 synthetic on Discovery's and P38's for a few years now.

It's more the api rating I was curious about.

Have ordered some gl5 just in case anyway

Henry_b · Mar 23, 2021

discool · Mar 24, 2021

domino said:
It's more the api rating I was curious about.

Have ordered some gl5 just in case anyway

It lucky you haven’t used it than, its GL4 for the old LRs

jamesmartin · Mar 24, 2021

domino said:
So, I bought some Westway 80w90 Gear Oil - mmarked as API: GL4.

Doing a bit of searching, some people seem to suggest the P38 need GL5. Others make no mention of it. RAVE makes no mention of it and simply states "Texaco Multigear 75w 90R" - no mention of API.

What is the *correct* fluid for the front and rear diff before I open this container?

makes no difference theres no yellow metal in the diffs

allanw · Mar 24, 2021

domino said:
It's more the api rating I was curious about.

Have ordered some gl5 just in case anyway

The synthetic I use has the highest spec anyway. GL5. I think the GL4 info may be out of date and was the highest spec at the time of Rave or handbook publication? Likewise with the API rating for the engine oil.

domino · Mar 24, 2021

So... Gl4 or gl5?

tomcat59alan · Mar 24, 2021

domino said:
So... Gl4 or gl5?

There's only one way to decide. ..FIGHT.

Harry Hill has a lot to answer for.

domino · Mar 24, 2021

tomcat59alan said:
There's only one way to decide. ..FIGHT.Harry Hill has a lot to answer for.

Lemme look out my oversized collar

But seriously someone must know what they've been putting in!?

tomcat59alan · Mar 24, 2021

domino said:
Lemme look out my oversized collar

But seriously someone must know what they've been putting in!?

Do you want to rephrase that ??

Rubberknees · Mar 24, 2021

tomcat59alan said:
Do you want to rephrase that ??

No I quite like the way this could pan out

Grrrrrr · Mar 24, 2021

domino said:
Lemme look out my oversized collar

But seriously someone must know what they've been putting in!?

For me? 75w 90r from Smith & Allan. Replace every 10k miles.

domino · Mar 25, 2021

Grrrrrr said:
For me? 75w 90r from Smith & Allan. Replace every 10k miles.

But what's the api rating?

romanrob · Mar 25, 2021

I used 80w90 GL5 last time

Grrrrrr · Mar 26, 2021

domino said:
But what's the api rating?

Says GL4 / GL5 equivalent. You can ask the question at the bottom of this page:

https://www.smithandallan.com/produ...--fully-synthetic-ep-75w-90-gear-oil-gl4-gl5/

domino · Mar 26, 2021

romanrob said:
I used 80w90 GL5 last time

That's what I'll go with then!

P38-DFX · Mar 28, 2021

GL4 is more for axles/gearboxes with brass/bronze components, whereas GL5 will do more harm. But as the P38 diffs don't have any such material in, GL5 is fine. I run 75w90 GL4 in min as its what I use in all my other cars.

domino

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allanw

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domino

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Henry_b

Think outside, no box required.

discool

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jamesmartin

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allanw

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domino

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tomcat59alan

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domino

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tomcat59alan

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Rubberknees

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Grrrrrr

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domino

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romanrob

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Grrrrrr

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domino

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P38-DFX

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