Thread: Sticky Manual Gearbox issues in Defender.

Interesting re the clutches, Trev.
Teflon, as used on frypans, etc, apparently requires quite a bit of heat and pressure to make it stay there. (far more than is ever experienced in any engine)
This is part of the claims against Slick 50 and Nulon, et al, that the PTFE they use is a solid suspended in a carrier (mineral oil), and therefore cannot work as claimed. DuPont, the inventors/makers of PTFE are pretty adamant about this. In fact there have been cases of it agglomerating and plugging oil filters in cars.
I used to use the stuff years ago, but when I was racing (cars) I was product sponsored with my oil and was warned off using anything in it. The stuff I was using was wickedly expensive, and one thing they (Neo) and in fact any oil industry person has told me since was that teflon doesn't work. If it did, they'd use it ! Some of the compounds the oil industry uses these days is pretty trick (and costly).

The additive package used in oils is pretty finely balanced with what the tribologist that blends it feels gives the best compromise (as everything is) in the intended application.

Moly appears to be a much better friction modifier as it plates metallic surfaces which are under pressure/load. Redline use a very high level in their engine oils, and talking and listening to some rival blenders, they feel that this, along with other EP and anti-wear additives, is what tends to make it so good in very highly loaded areas like cams and cam followers. The moly they use is a soluble (expensive) version, not molybdenumdisulphide (MoS2). This plating action is why moly is almost never recommended for wet clutches, although I believe soluble moly can be successfully used as part of the additive package.

I still think Syntrax is way too thick, and I wouldn't be game to use it, (although I use it in the diffs and t/case, as well as the t/case in the Patrol). Just compare the actual viscosities of it, Syntrans, MTF94 and any ATF at 40*C and 100*C, and remember that the gearbox was originally designed to use an ATF. (which isn't that great in a MT, but thats another story :wink: )

I think the original oil (Texaco MTF94) should be the best for the M380 gearbox. Having done a search on all the similar oils I could think of, this seems to have the best viscosity index.

My gearbox was very crunchy as well, when new, and I also experienced the tendency for it to be hard to select 1st after reversing. It has improved greatly after 10,000k's or so with the original oil still in use.

Castrol Syntrans 75W/85 should be OK. although it is a little higher in viscosity than the MTF94, and a bit more expensive.

I think I will stick to the MTF94, which is available from Caltex outlets, if you want to do your own servicing.

Cheers,

Lionel

viscosity index isn't the be-all of rating a lubricant.
You have to be a little careful at times, as an oil like Syntrans has a lower viscosity index than MTF94 as it doesnt contain any, or very little viscosity index improvers which tend to shear quite rapidly in a gearbox application.
Redline don't use any either.
I've used MTF94, Syntrans, Redline MTL and a brew of MTL and MT90 (to combat too thin oil at +35*C ambients-no oil cooler), and Syntrans had the best up shift charcteristics of them all.

Fair enough! If you've tried all these oils then you're in a good position to make a judgement.

I might give the Syntrans 75W/85 a try myself at some stage.

Cheers,

Lionel