Well I'm overwhelmed! ;-)
Don't get me wrong, I didn't expect my questions to provoke as much discussion as nerdy geeks talking about Star Trek would...
But still... I'm not about to pout and scweam and scweam about it. I can accept traffic is light, here and there's never any guarantee that you'll get your questions answered.
For what it's worth, I wasn't exactly expecting somebody to be able to answer everything in one reply - I thought perhaps the odd person would know something about selective bits - bit that's life, it's cool.
I must confess, other forums I've been involved in for other cars, have had more traffic and responsiveness for similar types of enquiry, but I guess where cars are more mainstream, and / or perhaps have more of a following, there will be more traffic.
The particular car I was initially interested in, I'm probably not about to bother about, now - although it was in very nice condition - inside and out, and the service history was good (although not quite completely as up-to-date as it might be - the dealer still seems to be touting it as having FSH, though - that's dealers for ya!) I did notice something of concern. When I look at used cars, I always have a good look under the bonnet, as well as being as thorough looking at the interior and exterior as I can.
I'm no mechanical expert, but I do have a rudimentary grasp for how things should look, and I always have a look at the oil, autofluid, coolant and the rest. I noticed that the autofluid as pretty black - I don't mean just a dark brown, but pretty black. Don't get me wrong, with a car of this age and mileage I wasn't expecting cherry red, but I've not yet seen a true black. I noted this, but put it in the back of my mind, and I thought I'd see how it was when I drove it.
I noticed when driving that it seemed ever-so-slightly to be slightly lethargic at moving on no, or light throttle - didn't seem to creep as much as some, and definetly not as much as my own car - I did consider that the LS400 was a big heavy car, and when it first truly noticed, it was whilst queueing on a fairly steep incline up to a roundabout. It seems there was a slight bit of slippage in first - in all other ways, though, the autobox seemed completely fine - no clunks or rough changes, no obvious slippage in other gears, no reluctance to kick-down.
Thinking about this, later, this and the black autofluid troubled me - black is bad for autofluid - something has happened for it to get black, as opposed to merely the red dye breaking down over time, and the fluid being a brown colour. I spoke to a local autobox expert and they were reserved and said they'd not had much trouble with Lexus gearboxes, but they agreed - black was bad. And said it would be hard to know whether this was a minor problem easily rectified, or whether it suggested impending doom.
So with that in mind, I won't bother with that particular example - which is a shame, because in all other respects, it was a fine example. I don't want to buy one, and be worried about having a big expensive failure imminent.
I do wonder what may have happened to it - possibly towed for whatever reason, and not had the proper precautions taken - or perhaps just one of those things. I know with my current car, main dealers seem very reluctant to do autofluid changes as part of ongoing servicing ('cept for use in harsh or commercial conditions - eg as a taxi) - so I suspect that in many cases it doesn't get done, unless the owner specifically insists. Perhaps this contributes to the odd case where things look slightly awry.
I did look at another LS400 same age and plate (P reg) - more miles, though - slightly over 150k miles. The autofluid on that was a more encouraging brown colour - but the rest of the car looked a whole deal more tired and unloved. Scuffs on bumpers, bodywork unloved - evidence of chips on the edges of the doors, so the previous owner obviously hadn't been that careful. The mileage wouldn't have necessarily put me off, but the condition just made me feel like it hadn't been looked after - although it looked OK from the mystical "5 yards" ;-)
So I'll keep looking, there's another one not to far away I might look at.
My reasons for wanting an LS400, being that I've always liked the bigger cars like the BMW 7s, the S Class Mercs and the A8s, but the LS400 seems to offer that sort of class of car, perhaps a bit more anonymous and less "in your face" which quite appeals, too, and having the famed reliability and build quality that's associated with the main Japanese car manufacturers.
If anyone has any feedback on any of my questions in the original post - I'd be more grateful, but if not - hey, that's life.
Cheers
Dave