[domino]

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]

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

 

[domino]

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]

GL4

 

[discool]

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]

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]

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 I think the GL4 info may be out of date and was the highest spec at the time of Rave or handbook publication?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]

So... Gl4 or gl5?

 

[tomcat59alan]

So... Gl4 or gl5?

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

 

[domino]

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]

Lemme look out my oversized collar

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

Do you want to rephrase that ??

 

[Rubberknees]

Do you want to rephrase that ??

No I quite like the way this could pan out

 

[Grrrrrr]

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]

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

But what's the api rating?

 

[romanrob]

I used 80w90 GL5 last time

 

[Grrrrrr]

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]

I used 80w90 GL5 last time

That's what I'll go with then!

 

[P38-DFX]

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.

 

[Frank_38]

Good evening everyone,

I have to admit that the choice of oil is really bothering me.
I would also like to change the diff-oil now.
Currently there is:

LIQUI MOLY high-performance gear oil (GL4+) SAE 75W-90

or

LIQUI MOLY Fully synthetic gear oil (GL5) SAE 75W-90

What do I use now? GL4+ is GL4 and GL5 together?

 

[miktdish]

A 4 year old thread ressurected ....

You use a 75W90 oil.
Wether is has Molybdenum in it or not will make little to who-ha of a difference.
Semi synth or fully synth, it doesn't matter it's in a differential of a road car in the UK.

If you were racing or pulling a 3 ton load around in a quarry i'd say go for the fully synth and change it every year.
Otherwise 75W90 is fine.