Oil change
 

my cars on 134,000 miles now, always change the oil every 4-6k miles. I tend to use 10w-40 semi synthetic but I've Seen threads saying don't use synthetic oil in these engines and some saying use 5w-40 because it circulates faster especially during cold days and lasts up to 10k miles. Should I stick to using 10w-40 or swap to 5w-40? Thanks.

stick to 10w/40. it is the recommended oil for these engines. it's what they are designed for. plus using thinner oil may make the big end bearings rumble and or oil to seep past the rings as don't forget the wear on the engine has worn for the thickness of 10w/40
i've never had a problem with mine and almost on 137k although in winter i do tend to let it warm up a little longer than i do in the summer :)

Okay thanks I'm a little obsessed with keepin my engine healthy With it's high milage dont want it to give up yet lol.

I'd go for a 10w40 semi synthetic - decent brand too. I ran a 5w40 fully sythnetic in my 8v and I felt it wasn't thick enough. 10w40 is generally cheaper than 5w40 too

This 100%
I run 5w30 for a while after 10w40 and along the motorway was horriable felt much ruffer so drained it out and put 10w40 back in it.