Correct oil? 5W30 Fully synth?

[King Fisher]

Hi guys, Nick has been using Millers 10W40 Semi Synthetic oil in his S2, seems to be fine using it too. Before that, he used cheapo Halfords 10W40 Fully Mineral, which also did the job fine. However, his plaque in the engine bay states Century 20W50 Mineral? And Autodata states 5W30 Fully Synthetic for the Cologne 2.9? What is correct, or will anything do as long as it's changed regularly?

Cheers,

Tony

[phillpot]

Can of worms time again !

spec. plate in engine bay is over 20 years old, there was a lot less choice of oils when that was made.

a lot of people (me included) prefer a semi-synthetic, its an old fashioned engine and to a degree it needs an old fashioned oil (imho).

[mep12345]

Agree with Mike above, but I used 4W30 for a couple of years - found oil pressure low when warm, engine a bit rattly and difficult to seal rocker cover gaskets. changed to good quality 10W50 and it is far better (semi-synthetic in both cases), increases oil pressure across range and engine rattle gone completely

HTH

Mark

[King Fisher]

Thanks guys, I think Nick may stick to his 10w40 semi synth in that case. His oil pressure is between 25lb when idling and engine warm, and around 50lb when under load and the engine's warm.