And now we move onto converting my oil filter from a canister type to the spin on type. There are a couple of words of caution here, (one very serious), so you may wish to read carefully.
Changing the crappy canister type filter for a spin on one has been covered plenty on this forum. It's isn't really a difficult job, (or at least shouldn't be unless things go wrong), but there is a certain knack to it due to the fact that there isn't that much room to work in.
First tip is to turn the steering to either full left lock or full right, (sorry, I cant remember which way now). This will give you that extra couple of cm clearance needed.
Second tip is to buy a proper oil filter canister car removal tool like this;
http://www.machinemart.co.uk/shop/product/details/oil-filter-wrench-set-cup-style-15-pieceI've seen these tools sold as kits in Machine Mart or sold seperatly in Halfords. I didn't buy one, but in retrospect I wish that I had.
What I did do was use a regular 12 sided 27mm socket to try and get the cap off, attatched to a 28" long breaker bar. All this did was start to round off the nut on top of the cap. (NOTE; even with the steering turned to full lock, there isn't much room to swing the bar).

Next I decieded to try using a 6 sided 27mm impact socket. This still didn't budge the bloody cap

Ok, plan 'C', and now I'm starting to lose my temper a little.
Forget the socket, just use the 1/2" square end of the breaker bar allied to some rather colourfull language and threats of extreme violence.
FAIL! All this did was split the cap in two, without actually unscrewing it at all;

At this point I'd reached Defom 5 so got the angle grinder out to teach this oil filter canister exactly who was boss.
To be honest this isn't exactly the safest way to go about removing the canister, but because I hadn't used the correct tools for the job, it was about the only option left. I dread to think of the consiquences(sp?) of dropping the angle grinder whilst stood / laid underneath it

but eventually I managed to cut the bugger off;

You can just see in the picture above the 'hex' drive bolt that bolts the base of the canister to the block. This is a 12mm hex. Nothing else would have got my canister off.
Once my canister was removed, here's what was left of it. You'll note the old oil filter, (I dread to think how old it is!) next to a new canister type filter. This is because at first I wasn't going to change from a canister filter to a spin on one, so I already had the new canister oil filter.


Old V New oil filters;

And the parts needed for converting to the new type of spin-on oil filter. Don't forget to use some decent stud-lock for the stud that bolts into the engine block;

There are two different types of spin-on oil filter. BE VERY CAREFULL THAT YOU BUY THE CORRECT ONE.
After changing my oil cooler I didn't buy the correct type of oil filter. After fitting and within 10-20 seconds of starting the engine, the (wrong type) oil filter popped clean off. Luckily the vehicle was still stood over my inspection pit and I had somehow sensed that something wasn't quite right so my hand was already on the ignition key ready to turn the engine off. I was very lucky that no damage was caused. I dread to think what would have happened at 80mph in lane three of the motorway

According to the friendly parts chap at Vauxhall there is two different strength valves inside the two different oil filters. The one with the weaker valve doesn't have the strength to withstand the V6's oil pressure, hence pops off.
I'll be going to collect the correct type of oil filter tomorrow so I'll post up clear pictures of the right and wrong type next to each other for clarity.
Anyway, mouting stud Loctited in place, left 24 hours to set, then new spin-on filter filled with fresh oil, (GM own brand 10w/40 semi synthetic) and put in place, (and obviously 6.25 litres of fresh oil in the sump).
Job jobbed as they say


EDITED TO ADD;
A picture of what was left of the oil filter canister cap after I had had to butcher it.
