old renault trafic

Sounds from your description that the cones in the syncro may be worn. Find someone who knows about this type of trans but you may require new cones in the syncro's. Oil additive or synthetic wont help you if this is the case, also if the drainplug has a magnet on it, check for parts of teeth, lots of fine metal parts etc. If the oil level has got low due to leaking seals or lack of maintenance the whole thing may require overhaul.
Regards Kev.

thanks for you comments kev ; however this being a very low kilometrage vehicle , carefully used , on a chassis designed for commercial use , it is hard to believe that wear is the problem , especially as the gearbox oil is stated as never needing changing [ in reality it has been changed ]
having had previous vehicles with worn synchro , the symptoms were the opposite , i.e. the cones would allow the gears to engage too soon for the revs !!

Make sure the clutch is fully releasing.

here's a link from bobistheoilguy.com that might be of inthttp://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=16;t=002665;p=0erest to you

try it again

last call for this urloil formula

great link thanks !sounds like I am not alone

will try the penzoil mix and see how it goes

thanks again