LT77 Oil

tetlow · Post by **tetlow** » Tue Jun 12, 2007 7:59 pm

Sorry to raise this old chestnut but...

I have just bought a new rebuilt LT77 from the MGOC. I am told to fill it with Castrol Classic 20-50W.
Is this Ok?

It would be handy as the engine uses the same.
Dave

Pocket rocket · Post by **Pocket rocket** » Tue Jun 12, 2007 8:50 pm

I don't know if you'll ever find a definitive answer to this one . I have checked the two Austin Rover manuals i have and I am even more confused than before as they give different advice

The 1986 edition states thta a manual box should use :

Unipart ATF ; Castrol TQF ; Esso ATF type G ; Fina Purfimatic 33G ; Texamatic type G ; Duckhams Qmatic ; BP Autran G ; Mobil ATF 210 ; Shell Donax TF

The 1981 edition states the following :

BP Gear 90 EP ; Castrol hypoy Light ; Duckhams Hypoid 75 ; Esso Gear GP80W ; Mobilube HD80 ; Fina Pontonic MP SAE80 ; Texaco Multigear lubricant EP80 ; Shell Spirax HD 75W/80W

However the footnote says that if drained then the box must be refilled with Hypoid 75W gear oil but where this is not available use Hypoid 80W

My hair is now pulled out!

To top it all i was previously advised to use Dexron II and my Lt77 seems to work fine on that.

ramon alban · Post by **ramon alban** » Tue Jun 12, 2007 8:56 pm

Try page 3 of the PDF available from here. It works.

http://www.vintagemodelairplane.com/pag ... box01.html

tetlow · Post by **tetlow** » Tue Jun 12, 2007 9:14 pm

Thanks Gents
I am not sure what to do as I have a 12 month warranty to worry about if I don't use the 20-50, but a lot of people have said what they use and I have not heard of any one using 20-50.
I should use the later oils and change back to 20-50 if I have a problem.

Dave

Post by **katanaman** » Tue Jun 12, 2007 11:59 pm

EP oil used to be the recommended but the gearboxes were terrible with it so they then swapped to ATF. That's why the two manuals differ.

As said you will never get a completely right answer to this question. Personally I found Castrol SMX to give a very good shift.

Personally I never liked putting molly in a gear box. The syncros require friction to work and molly reduces that. I know molly is great stuff but I just cant help wondering that if it is so great then why don't the oil manufacturers use it. When they can charge £30-£40 a can for premium oil or more then I am sure it isn't for cost reasons.

At the end of the day you have been told to use 20/50 so use it as your warranty depends on it. There is certainly a lot worse that you could put in.

ramon alban · Post by **ramon alban** » Wed Jun 13, 2007 8:51 am

katanaman wrote: Personally I never liked putting molly in a gear box. The syncros require friction to work and molly reduces that. I know molly is great stuff but I just cant help wondering that if it is so great then why don't the oil manufacturers use it. When they can charge £30-£40 a can for premium oil or more then I am sure it isn't for cost reasons.

Marki, as you say, there is no right answer because different treatments work for different circumstances. Since '94 I have used, ATF + white spirit to flush my Vitesse box (on ramps), Mobil 1 or Castrol RS + Moly gearbox treatment as lube, changed twice more in that 13 yr period.

The gearbox was transformed and remains perfect without baulking and smooth as silk.

I believe the reason why oil manufacturers would not put moly into oil is because it would be inappropriate to have such friction-free mixture in a new engine/gearbox as it would prevent bedding in.

Ramon
http://www.vintagemodelairplane.com

kiwicar · Post by **kiwicar** » Wed Jun 13, 2007 9:34 am

On the use of Moly... you should avoide using the stuff where you have ball or roller bearings, it is ideal for plain bearings and gear teath.
Molly (molibdinum disulfide) forms microscopic spheres (which are very hard) that act, in plain bearings like microscopic ball races, that is why it is such a good lubricantin for these bearings.

This is also why you should not use it with real ball races (or roller races), the spheres will pit the ball/ roller's surface and leave it like an orange for texture, in the case of a hardened roller/ball bearing it can lead to the surface cracking all over and can lead to shattering of the balls hardened surface (My brother's PHD paper many years ago)

I also know all about cavitational erosion of white metal bearings if you have trouble sleeping sometime!

Mike

chodjinn · Post by **chodjinn** » Wed Jun 13, 2007 11:17 am

Redline MTL.

I was advised by an SD1 racer to use this. Looks the part, haven't used it yet tho lol

sidecar · Post by **sidecar** » Wed Jun 13, 2007 4:35 pm

chodjinn wrote:Redline MTL.

I was advised by an SD1 racer to use this. Looks the part, haven't used it yet tho lol

I second that!

(Apart from I have used it)

ramon alban · Post by **ramon alban** » Wed Jun 13, 2007 6:59 pm

kiwicar wrote: and can lead to shattering of the balls. Mike

I cant think of anything more disconcerting.

Ramon