Diff Oil

[TIMS]

Guys

 

Diff out & drained, now I need to re-fill it.

 

Have spent the morning driving round motor factors looking for Hypoy 90 with absolutely no sucess.

 

Lets get this out of the way up front - I know I need GL4 and not GL5.

 

Castrol website does not seem to list any straight 90.

 

Halfords will sell me Castrol EP 80W/90 GL4, but I thought that I needed Hypoy not EP? (there again the Brown Bible lists Shell Spirax 90 EP, and BP 90 EP so perhaps EP is ok?) and do I really want a multigrade?

 

Frost have Millers EP 80W/90 GL4.

 

The question is, Can I be happy with EP 80W/90 or where can I get Hypoy 90 as per the Brown Bible?

 

Thanks in advance for your responses.

 

Regards

 

Tim

[88V8]

Came across a pint squeezy of Hypoy 90 in the garage the other day. Put it back on the nostalgia shelf.

 

As a diff, I think it's just a diff, nothing special, EP 90 GL4 will be fine. Comma do one in a red bottle as I recall ?

I have sometimes used 80/90 in my Landy but as you can only do a total refill with the TR diff out, would seem a shame not to get the proper straight 90 for it.

 

Ivor

 

Edit: the Comma I have is EP80/90 which confusingly they describe as 'Hypoid'. The olde squeezy is Castrol EP80 which they label Hypoy and describe as Hypoid Light. I thought Hypoid and Extreme Pressure were different things? Where's our oil expert whem we need him...

Anyway, the straight 90 I have is made by Granville. If you can get it.

Edited November 15, 2008 by 88V8

[Alec Pringle]

Hi Tim,

 

Comma EP80W-90 Gear Oil, which is GL4 spec, will do you nicely . . .

 

http://www.commaoil.com/

 

go to Products, then Oils & Lubricants, then Gear & Transmission Oils, then the GL4 spec is on the top right.

 

Good stuff, and widely stocked by motor factors. I've been using Comma since way back when, always reliable.

 

Cheers,

 

Alec

[TIMS]

Ivor

 

Thanks for the reply.

 

Found this on a Dutch British Sportscar site.

 

"Castrol EP90 Extreme Pressure GL4 gear oil now replaced by EP80/90."

"Castrol EP80/90 Extreme Pressure Multi-grade GL4 gear oil (will replace EP90 when stocks are exhausted) For manual transmissions and some Hypoid differentials"

 

So it sounds as though the multi grade is ok.

 

I also found, from Holden, Castrol Classic 1840 EP90 "Castrol Gear Oil - Manual EP90, For manual gearboxes, hypoid and non-hypoid rear axles where EP90 is specified" But I can't find any other detail on this oil, GL4?.

 

The search goes on.

 

Regards

 

Tim

[Richard Crawley]

I thought Hypoid and Extreme Pressure were different things? Where's our oil expert whem we need him...

Anyway, the straight 90 I have is made by Granville. If you can get it.

Hypoid is a method of spiral gear cutting so it specifically refers to the type of gears which were developed to minimise gear whine; a familiar characteristic of straight cut gears. Due to the high shear action of Hypoid gears they MUST be run with Extreme Pressure (EP) oil or the protective oil film will break down leading to gear damage. Hypoid is the gear technology; EP is the oil so they effectively mean the same.

[TIMS]

Alec

 

Thanks for that one. Now which of the factors was it where I saw the Comma?

 

Richard

 

That explains things. So an Extreme Pressure oil is what is needed for Hypoid gears. I understand.

 

As ever, the Forum explains, assists and educates.

 

Regards

 

Tim

[RogerH]

Hi Richard,

thanks for posting the EP / non-EP answer. I was building up to an answer but yours fits the bill perfectly.

 

From what I have found out in some very old books the hypoid gear assenbly was designed to give an assembly physically smaller than a normal bevel gear for the same power transfer. The reduction in whine was a very useful side affect.

 

Roger