engine oil

[Keithver]

I have just rebuilt the engine and am using Castrol running in oil for the 1st 1000km
When I change the oil and filter, should I fill up with running in oil or normal oil. From what I have seen on the forum 20w/50 seems a popular choice
On a slightly different topic, I have heard some reports that Castrol oils are a little sludgy and might gum up the works - is there anything in this. If so what should one be using.
on page 38 of the owners manual, the suggested oils are 10w-40 and 10w-50

[LCR1967]

I rebuilt my engine a couple of years ago and used Motul 15W50 from the very start. Change the oil and filter after approx 1500km.

[Spider2]

I am no expert on oils but I agree with the comment about Castrol oil. In the 60's and 70's Castrol GTX was the trendy oil to use. I found it sludged up my TR4 badly. Perhaps it was so good it was in fact de-sludging it.  I have used semi-synthetic 10-40 for years and it seems good.

[davidwheeler]

Me too from my local motor traders.   I do not wish to subsidise Castrol's advertising bill!

[Keithver]

thank you all