Gearbox Oil Recommendations

[DarthMJH]

Hi,

Can anyone recommend gearbox oil for my 1973 911T with a 915 box. I would like to change the oil as I don't know when it was last changed.

Thanks for looking.

[911hillclimber]

IMHO standard spec, if simply a road car.
I was given this advice 27 years ago and by several true experts since.
I also do this in my race only 915 box.
If it has a plated lsd then call Mike at Mike Bainbrige Engineering

Never had an oil related box failure in 28 years with 3 1973 boxes.

[MBEngineering]

HI DarthMJH

you can use EP80 , or EP90 , if this is not available 75/90 semi, is the box running OK, as in gear selection or noise from bearings or gears, check the drain plug on the oil change a small fuze build up on the mag' is usualy the syncro bands are getting a little worn, take the car for a run before draining to warm up the oil

has the box a LSD if so Castrol B373, you will need 3Lt for a change, try to find 1Lt cans/bottles with a pipe/spout to put the oil back in, you will find that the Std Porsche wheel brace will remove the drain plug and the filler OK.

do not tighten the plugs as if they are wheel nuts, the plugs have a taper thread and just need to be nipped up, you feel it get tighter the more the plug screws into the case.

regards mike

[210bhp]

And there in one post, condensed into just a few words with no verbiage, is 50 years experience.

Keep posting Mike, and thank you.

Regards
Mike

[Ian Comerford]

I went to Motul 75/90 Tecnosythese (spelling..) after using Swepco 201 for a while in my 915. The Motul blurb reckons it is for hard shifting gearboxes so seemed like a good idea. I think it felt a bit better but it is worth swapping it out more regularly than most people do.
http://www.opieoils.co.uk/p-897-motul-m ... f-oil.aspx
Ian

[911hillclimber]

In my experience Swepco 201 is a retrograde move.
Mike said stock Castrol oil stock grade so good enough for me any day.

[Gary71]

Totally agree. Stock Castrol EP80 oil every day. I went through the snake oil Swepco phase and got over it after advice from Mike many years ago.

He knows what he is talking about!


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[DarthMJH]

Thanks all for the advice.
Mike, the gearbox isn't noisy but when it gets hot, selecting first and second gears can be a little stiff. Not sure what that is?

Mike

[alfietom]

Hi Mike,
My 915 box was 'a bit notchy' and selection could be difficult at times so went down the route of a Gear Oil change. I just used standard Castrol EP90 oil and was amazed by the difference it has made. The box is now sweet with easy gear changes.

I just love an easy fix.

[C3s]

Sounds like a fairly easy satisfying winter evening job. Does anybody know the correct refill amount for a 915 box? Thanks

[Gary71]

The manual says 3 litres, but you fill it with the box level until it comes out of the plug on the side.

[DarthMJH]

I changed the oil today, it was black so hadn't been done for some time. There was a small amount of swarf. I will be driving round Yorkshire over the weekend, so will see what it is like.

[C3s]

Aaah, the good old filler/level plug, thanks. Great failsafe as long as you're on a level surface

[911hillclimber]

The challenge is getting it in, very tight access as difficult to get the tin vertical.
Good game.
Does 90 make a shift difference over 80 at normal summer temperatures?

[C3s]

I checked my personal stock today & was surprised to find an unopened gallon of EP80/90 so presume that's right in the middle? And has to be better than the 20 year old stuff that's in there