If it is a K series then no, do not re-torque the head bolts.

Where is the leak as it may well be the cam cover bolts which need tightening.

Depends what you are looking for. You can get cheap ones which are not thatcham approved for insurance through to more expensive ones that are. Unless you get a qualified fitter to do the fitting and certify it, the thatcham approved ones will not be recognised by your insurer, so you may just want ...

Lost of cost in getting the K series turbo to 200bhp.

Cheaper to get the VVC to 180bhp which would overall give you a better performing car.

As mentioned a good quality 10w40 semi synthetic oil is what you need. Some examples are:

Castrol Magnatec
Shell Helix
Mobil Super

And as mentioned, ensure he does NOT re-torque the head bolts when you take it back.

Yes you do. Or you will fail the MOT. It's MEAN'T to have a cat in for your MOT but i've known places in the past still pass cars so long as they meet the emissions. ;) regardless its 4 bolts to swap it back over so worry about it at MOT time :D That is the point I was making, it won't meet the emi...

Yes you do. Or you will fail the MOT.

In answer to the performance question, no, there is no performance benefit whatsoever on that engine. It sounds different which gives people the impression it has made an improvement, but in reality it hasn't at all.

VVC will have the MkIII dash as opposed to the turbo's MkII one.

The later cars had a different colour interior.

Other than that its the engine.

It is very sad.

It was off Mark that I bought my Coupe 7 years ago. The car actually belonged to his wife Alison.

Mark was an absolute genius and such a down to earth and honest guy.

Mines been straight through 6 in my ownership and coming up to due its 7th.

Has only done 50k in that time though so you win the milage part.

The Vauxhall version based on that Ascona was the MkI Cavalier.

We had a 2 door saloon version in the family which was bought new in 1977.

I assume that's an Opel Ascona?

Congrats!

Brake and steering fluid every 2 and coolant every 4 with the newer longer life stuff.

I bet it does get missed off by many garages though.

Yep, used that method for 6 years now.

Polystyrene can be shaped to fit and is a firm base. Wrap it in something so it doesn't make a mess (bin liner is fine).

That then gives a level base that almost any booster seat will be able to use and be safer than many other cars.

Will be interesting to see what you come up with.

You are local as well, so if you need someone to have a look at bits and confirm fits etc (may help in selling) then let me know.