Horrible knock!!

[jimmyV8]

After using my 98 400 Chimaera a fair bit over the weekend it seems to have an awful intermitant knocking noise coming from the engine. It only appears to happen when the engine has totally warmed up and if returned to idle after a period of time appears to disappear. It had happened a little while ago but with an oil change seemed to sort it out, i guessed it was possibly a sticking tappet? The oil was a little low and the only grade i could get at short notice was a 0w 40. Which i used to top it up with, im guessing this is maybe a little thin. I think an oil change is in order. Has anyone else experienced this and what grade and brand of oil would you recommend? Thanks

[daz the plumber]

is there some one stuck under the bonet . , may be some one is trapped !

[Boosted LS1]

daz the plumber said:

is there some one stuck under the bonet . , may be some one is trapped !

A dwarf with a big hammer perhaps?

[winters]

I can't really advise on your knocking problem - but sounds like something you want to get properly diagnosed. But on oil, I use 15/50, and was told that was perfect when I got the car serviced at a (respected) TVR garage (its a '99 500 - so comparable age to yours). Was also told 0/40 was definitely too thing. I used Mobil1 Motorsport, but only to ensure the synth oil was compatible with that which i was told was put in previously (I was only topping up - not doing a clean/change). Opinion on here seems to be that mobil1 is priced for the brand and that there are cheaper alternatives which are just as effective. I'm sure others will be along to recommend specific oils.

Good luck getting it sorted. Hopefully nothing too serious.

Nige.