(Home) Tyre pressures & overdrive

Hello everyone - I've just bought my first townace and drove it home yesterday - it's great to know that you are all out there! Myself and my family of young boys love the van, but are bemused with some things...what is overdrive? I was told it would increase fuel consumption a lot, but it seems to reduce the revs by about 1000 when I switch it on - is it like a 5th gear?
Whyt does the green turbo light switch on by itself?
Also - the tyres need pumping a bit - but I can't find the right tyre pressures? Any advice on where to look? The model is a 2L 4x4 Diesel 1992.

She seems a bit 'grainy' over 50mph - I checked the oil dip stick before buying and the oil was black - I was told this is normal for a diesel - have I been duped??

Hope somebody out there can help....

- (#5120) mary morris, 17 Aug 02

tyre pressures are on the door pillar, but 36- 45psi depending on personal preference seems to be the consensus.
O/D is fourth gear. Leave it on...
the green light is telling you that the turbo is working. Normal!
And yes, black oil is normal.

- (#5121) david miller, 17 Aug 02