Gearbox oil

[arthur67]

Hi just checked the oil level in the +2s 130/5 and I am sure it is EP oil.The car has not been on the road for 16 years and I am restoring it.My problem is do I leave it or do I drain it and refill with 20/50.what do other people think.
I have taken it for a very short run and it seems ok if a little notchy.Thanks for any advice Arthur

[alexblack13]

Hi Arthur,

There is a guy called Graham Boulton who is ex Lotus and was responsible for building the lotus 5 speed boxes. He still does and is widely recognised as 'the man' when it comes to rebuilding and Info' etc. He apparently holds most of the spares available for the 5 speed too... So ... When I bought a 5 speed Lotus box to fit to my Sprint from Susan Miller, who you will get to know if you don't already. She sold it to me fully reconditioned and warranted. Rebuilt by Graham Boulton.... I had a few discussions with Graham and he told me the gearbox (BL maxi internals) was designed to run lubed by the engine oil. Hence the recommended 20/50..

I ran the box in a little then changed the oil to Redline MTL.. That does make a difference to the change / feel of the box.

The 'notchy' feel you refer to is fairly normal and typical of the gearbox. Some are worse than others. I have managed to get mine pretty good and not too far away from the 4 speed as far as change 'feel' is concerned.

So I would drain your gearbox and refill with a 20/50. Graham recomm'd Duckhams..

Are you removing the gearbox during the restoration?

Alex B ....

[rgh0]

HI Arthur
I run my 5 speed with Redline MTL. Improves the change compared to 20w/50 engine oil or other 75W/80 gear oils I have tried

While a gearbox "can" run on engine oil as the Lotus 5 speed internals were forced to do when used in the Leyland gearbox in sump design, a proper GL4 gear oil will always be better in terms of gear and bearing life and one like Redline that has the right properties also for best synchro performance will be the best.

cheers
Rohan

[arthur67]

Thanks for that info Alex and Rohan. I will have to put a new clutch so the gearbox might be coming out probably try leaving it in looks possible. Regards Arthur

[RichardHawkins]

Arthur,

I am not a gearbox expert, just a general mechanical engineer. However, I think Rohan is spot on as usual.

In the early days of BMC transverse engined cars with the gearbox in the sump, the oil had to be a compromise. I would expect a gear oil to be better suited to the application.

Richard Hawkins

[alexblack13]

OK guys I hear you but.... Mr Graham Boulton is THE expert on the Lotus 5 speed box. Of that there is no doubt...

Now.. I am the messenger here and I am passing on what he says. Which is. When the box was designed originally it was designed to run in engine oil. Not a box that was already in use and adapted, it was one of the early 5 speeders and was built to do a job and run in the engines sump..

It does NOT respond well to running in the viscous / heavy duty 80/90 gear oils of the day. (try it!!)

I was recommended by the man who rebuilt and warranted my box (the said Mr Boulton), to run the box on a good 20/50 which I did for about 1000 miles before changing and refilling with Redline MTL

Redline MTL is far and away the best to use in this box IMHO... ( and Rohan's...) And made a big difference to the gearbox shift / change action.

Now don't shoot the messenger eh no!