Well I've just done a service, and changed to 20/50 oil as recommended on here, and suprise suprise, no flashing light. The engine was definatly rebuilt, and to manufacturer specs as I done it all myself so there was no problems there. The oil that came out was clean as a whistle, no metal particles or anything so it's all still good in there..... I am now in the process of rebuilding my carbs and then setting them all properly, and adjusting to suit. But I've been driving it all day today and haven't seen the oil light flicker once.
It was cheap. I wanted 3.5 litres or so to refill the oil after taking the engine out.. And I was interested to see if there was any real temperature difference between 20W/50 and 30 weight in terms of running hotter.... not a lot... but there is the second oil cooler cutting in above 80C.
I remember back in the 60's when the new multigrade oils came in like the 20w50 from Castrol and Duckhams. Our old motorbike and car engines liked the new oils and they became the standard. I use 20w50 in my mgb and type 1 engine and they do well on it. The 20w50 is designed to maintain its viscosity at higher temperatures, but the sae 30 oil, thins down to dish water as it heats up.
