My own comments come from having changed the gearbox oil in my TR8 recently. Well, in fact I changed it in September 2012 to replace an unknown & decidedly suspect looking dirty mixture that was in the box, & I changed it again in January this year after about 2K miles as the box was out for a clutch job. Both times I used Motul Gear 300. The box has 50K miles on it, it works perfectly well but does have a slightly weak 3rd gear synchro.
The first change really did improve the smoothness of the box, although it was still baulky when cold. At the second change, I was surprised at how dirty the oil had become in that short time, but maybe it was flushing out the remains of the previous fluid as well.
Having refilled a second time, I must say I am really impressed with the improvement in the box. Still baulks a little from cold (& it has been very cold here over the last few weeks), but once warmed up it is really smooth. I have been especially pleased with the fact that the previously difficult 3rd gear synchro now shifts really easily after warm up even at high RPM, although it still needs care when cold.
So, Motul Gear 300 gets a thumbs up from me.
The second bit of info I have to share with you is from a guy I met at the NEC Classic Car show last November. This chap had worked for Leyland & latterly Land Rover on developing the LT77 & the R380 over a 28 year career including a great deal of research into the transmission lubrication & fluids to use. This is what he has to say about transmission fluid:
"When I was at Landrover developing the LT77 and the R380 unit we assessed various oils to give good gear and bearing life and smooth synchro performance. Together with Texaco we came up with the MTF94 as the best all rounder.I do remember assessing an Elf transmission oil that was also very good, so perhaps if you have the time and are still striving for more improvements you could try Elf.
Of course there are many, many influences on synchro performance, ie inertia of the clutch plate, design of the synchromesh system, coefficient of friction of the components, and sometimes the spec of the oil was an immediate no no to work with the design, so we never tried it. Don't forget that an arduous rig test which really proved the longevity of all components was carried out before we would recommend an oil for production, so I am sure you will find some advantage using the Texaco product.
Yes we did try ATF oil and it was good, but we favoured it only because it was able to run at a much higher temperature,and still maintain its viscosity and qualities. It also gave less resistance to the components which as you can appreciate these days is very important to fuel consumption, etc, etc.
The gearbox oil especially the Texaco products were designed for lifetime running, but like yourself I would change my transmission oil before that."
So there you go, from someone "in the know". Interesting comment about the ATF. Texaco MTF94 seems to be readily available here in the UK (try a Landrover dealer or specialist oil retailer), & not too expensive, so maybe some one who is thinking of a gearbox oil change will try it & report back.
Tony
<font size="1">1981 TR7 FHC Cavalry Blue
1980 TR7V8 DHC Jaguar Regency Red - sadly sold!
1977 TR8 FHC EFI Factory development car Inca Yellow</font id="size1">
